Showing papers in "Semiconductors and Semimetals in 1999"

Chapter 1 The Basic Physics of Intersubband Transitions

Abstract: Publisher Summary This chapter focuses on the basic aspects of intersubband transitions, with the main emphasis on linear absorption. An expression for the intersubband absorption coefficient is based on Fermi's golden rule for induced transition rate in the framework of the one-band effective mass approximation. The chapter discusses several experimental geometries that enable the coupling of electromagnetic waves to the intersubband transition, which in most cases requires a polarization component perpendicular to quantum well (QW) layers. The chapter discusses asymmetrically-shaped QW potentials, such as those induced by a vertical electric field or by the variation of alloy composition. A main feature of intersubband transitions is their δ-function-like density of states, which is a consequence of the same curvature of the initial and final subband. It is generally advisable to work with the dielectric function ɛ(ω) or the conductivity σ(ω) instead of the absorption coefficient, whenever the electromagnetic properties of a sample are to be calculated consistently or many-body effects in the absorption are to be taken into account.

Chapter 4 Quantum Well Infrared Photodetector (QWIP) Focal Plane Arrays

Abstract: Publisher Summary This chapter focuses on quantum well infrared photodetectors (QWIPs) that utilizes the photoexcitation of an electron (hole) between the ground state and the first excited state in the conduction (valence) band quantum well. The quantum well structure is designed as the photoexcited carriers escape from the quantum well and is collected as photocurrent. Larger intersubband oscillator strength and detectors afford greater flexibility than extrinsically doped semiconductor infrared detectors because the wavelength of the peak response and cutoff is continuously tailored by varying layer thickness. Various types of gallium arsenide–aluminium gallium arsenide (GaAs–AlGaAs)-based QWIPs, QWIPs with other materials systems, the figures of merit, light-coupling methods, QWIP imaging arrays, and some applications of QWIP FPAs are also reviewed in the chapter. Rapid progress is made in the understanding of intersubband absorption and carrier transport in the QWIP device structure and practical demonstration of large, sensitive, and two-dimensional QWIP imaging focal plane arrays (FPAs).

Chapter 3 - Metalorganic Vapor Phase Epitaxial Growth of Self-Assembled InGaAs/GaAs Quantum Dots Emitting at 1.3 μm

Abstract: This chapter discusses the growth of short-period superlattices using the atomic layer epitaxial (ALE) technique. The alternate supply similar to ALE growth is important for producing this type of quantum dot. The chapter reviews the growth characteristics of alternate supply (ALS) quantum dots, which are grown by an alternate supply of a monolayer or less with a sequence of indium arsenide gallium arsenide (InAsGaAs) and indium gallium arsenide (InGaAs). The chapter also introduces a new type of self-assembled quantum dots grown by metal-organic vapor phase epitaxy. Their growth sequence is unique as the group-III and group-V precursors are supplied alternately with an amount corresponding to one or less than one monolayer. The quantum dots also acquire great controllability in size and emission wavelength by an adjustment in the cycle number and the composition of buffer layers on which the dots are grown.

Chapter 5: Hydrogen Phenomena in Hydrogenated Amorphous Silicon

Abstract: This chapter discusses hydrogen phenomena in hydrogenated amorphous silicon. Hydrogen's property to saturate dangling bonds of the host material and thus to reduce the concentration of defect states is the role of hydrogen in amorphous silicon, germanium, and related alloys during the past two decades. Some important characterization methods such as infrared (IR) absorption, hydrogen effusion, and hydrogen diffusion measurements by secondary ion-mass spectroscopy (SIMS) are applied to various series of hydrogenated amorphous silicon films with greatly different hydrogen concentrations. Infrared (IR) absorption and hydrogen effusion measurements provide rapid characterization for the bonding configurations and the thermal stability of hydrogen, respectively, in hydrogenated silicon materials. The measured transmission spectrum is normalized to the transmission spectrum of the crystalline silicon substrate, and the absorption coefficient is determined by applying Lambert–Beer's law.

Chapter 3 Quantum Well Infrared Photodetector Physics and Novel Devices

Abstract: Publisher Summary This chapter focuses on (1) the physics of quantum well infrared photodetectors (QWIPs) and (2) related novel structures and devices. It discusses the concept of intersubband transition (ISBT) in quantum wells (QWs) and the wavelengths covered by gallium arsenide (GaAs)-based structures. The physics of QWIPs includes dark current, photocurrent, and detector performance and design. The chapter also details novel structures and devices, including multicolor and multispectral detectors, high frequency detectors, and QWIPs integrated with light emitting diodes (LEDs). Samples presented in the chapter are all made by GaAs-based molecular beam epitaxy (MBE). The QWIP approach is favorable and attractive in several areas, such as producibility, large arrays, multicolor and multiband, high speed, and integration. For a standard QWIP, the optimum well design is the one having the first excited state in resonance with the top of the barrier. This configuration gives at the same time both a large absorption and a rapid escape for the excited electrons.

CHAPTER 7 – Strain in GaN Thin Films and Heterostructures

Abstract: This chapter reviews the current understanding of stress- and strain-related phenomena in gallium nitride (GaN) thin films and heterostructures. It discusses their impact on thin-film growth if any physical property of thin films is affected. The chapter presents several examples to study the surface morphology of the GaN films, native defect formation, the incorporation of dopants, and photoluminescence. A growth cycle for thin films and heterostructures comprises three steps: the surface nitridation, the buffer layer, and the main-layer growth. The main-layer deposition introduces strain if its lattice parameter differs from the buffer layer at the growth temperature. Lattice parameters are usually changed by a variation of native defect concentrations or by the incorporation of dopants and impurities. Such point defects introduce hydrostatic strain components. Thus, hydrostatic and biaxial strain components coexist in the films and are physically of different origin.

Chapter 3 Vibrational Spectroscopy of Light Element Impurities in Semiconductors

Abstract: Publisher Summary This chapter discusses the vibrational spectroscopy of light element impurities in semiconductors The vibrational spectroscopy of these high-frequency modes has become an important probe of defects in solids as it provides information about defect structure and properties that cannot be obtained by other methods However, the restriction to lighter impurities than the host atoms is a limitation Nonetheless, the light elements include important dopants, many of the most common contaminants in semiconductors, and the constituents of common alloys The chapter describes the linear chain model for local vibrational modes This model explains how impurity-related vibrational modes reveal information about the microscopic properties of defects The practical issues involved in the measurement of local mode vibrations by infrared absorption or Raman spectroscopies are discussed

Chapter 1 - Theoretical Bases of the Optical Properties of Semiconductor Quantum Nano-Structures

Abstract: This chapter provides a theoretical background of the optical properties of semiconductor quantum nanostructures and emphasizes on how those properties vary from quantum wells to quantum dots and how they are influenced by the exciton effect. Semiconductor quantum wells in which a thin semiconductor film is sandwiched between different materials via heterojunctions confine electron motion in the two-dimensional thin-film plane. This two-dimensionality gives rise to new optical properties that are not observed in bulk materials: (1) such as optical absorption and gain spectra peculiar to the step like density of states, (2) strong exciton resonance clearly observable even at room temperature, and (3) large optical nonlinearity and an electric field-induced energy shift of the resonance, called the “quantum-confined Stark effect.” Multidimensional quantum-confinement structures, such as quantum wires and quantum dots, are expected to improve quantum-effect optical devices.

Chapter 4 Organic LED System Considerations

Abstract: Publisher Summary This chapter discusses organic light-emitting diodes (OLEDs) system considerations. The advent of organic electroluminescent devices advanced from a long history of development of organic photocondoctors (OPCs) for xerographic copy machines. While the organic solar cell has a similar mechanism as the organic photoreceptor, the OLED or organic electroluminescent (EL) device has a different mechanism. In the application of organic EL devices to practical displays, the chapter discusses three fundamental issues: (1) stability (lifetime), (2) power efficiency, and (3) full-color capability. The chapter summarizes the present status of both molecular OLEDs and polymer LEDs in terms of panel performance and fabrication processes. Although efficiency is considered as a strong pro for molecular OLEDs, progress in the efficiency of polymer LEDs makes it comparable to that of molecular OLEDs.

Chapter 2 Molecular Beam Epitaxial Growth of Self-Assembled InAs/GaAs Quantum Dots

Abstract: This chapter discusses molecular beam epitaxial growth of self-assembled indium arsenide/gallium arsenide (InAs/GaAs) quantum dots. The atom-like density of states in quantum dots should drastically improve the performance of optical devices, especially semiconductor lasers, and should also be instrumental in the development of novel optoelectronic and single-electron devices. Numerous challenges in quantum-wire and quantum-dot fabrication have been reported during the past two decades. The most straightforward technique is the quantum-well structures through a combination of high-resolution electron beam lithography and dry or wet etching. Self-assembling—a novel way to fabricate quantum dots—is the most promising approach in overcoming the various problems with previous techniques. This process exploits the three-dimensional island growth of highly lattice-mismatched semiconductors. In columnar-shaped quantum dots, where both narrow spectrum width and high-emission efficiency are obtained, low-threshold and highly efficient operation of quantum-dot lasers can be achieved successfully.

Chapter 2 High-Efficiency AlGalnP Light-Emitting Diodes

Abstract: Publisher Summary This chapter focuses on the development and performance of aluminum gallium indium phosphide (AlGaInP) light-emitting diodes (LEDs). The AlGaInP quaternary alloy system is widely used for visible wavelength optical devices such as lasers and light-emitting diodes (LEDs). AlGaAs direct bandgap red LEDs, first as absorbing substrate (AS) devices and later as transparent substrate (TS) devices, grown by liquid phase epitaxy (LPE) resulted in improved efficiencies of ∼10 lm/W (∼14% radiant efficiency). These were the first LED devices to take advantage of the efficient double heterostructure (DH) design and made outdoor applications such as red traffic-signal lights and automobile brake lighting a possibility. AlGaInP is an important optoelectronic material for LED and visible laser diode applications. Recent advances in GaN technology have provided efficient blue and green emitters, which make full color displays possible.

Chapter 5 Molecular Organic Light-Emitting Devices

Abstract: Publisher Summary This chapter discusses present state of molecular organic light-emitting devices (OLEDs) science and technology. The chapter describes the structural properties of these devices and their implications on device performance. The simple OLED configuration is the single organic layer device consisting of an electron transport layer (ETL) or hole transport organic layer (HTL) sandwiched between an anode and a cathode. Besides serving to transport carriers, the organic thin film also acts as the electroluminescent layer. The new device structures demonstrated during the past several years together with conventional OLEDs are building blocks for many different organic light emitters and full-color displays. The development of a transparent, thin film organic light-emitting device demonstrates a significant advantage of organic materials in realizing high definition, full-color, and head-up displays. The chapter also describes the fabrication, physics, and state of the technology of vacuum deposited molecular (i.e., nonpolymeric) OLEDs.

Stress effects on optical properties

Abstract: This chapter discusses the strain effects on nitride semiconductor compounds. The chapter describes some basic properties of strain and reviews some of the effects evidenced of intense investigations during the past decades of zinc-blende semiconductors. Residual strain-fields are always present in III-nitrides and in their related heterostructures. They can produce a reversal of the ordering of the valence band in bulk crystals under biaxial tension. The oscillator strengths of the optical transitions at zone center are extremely dependent on the biaxial strain. Growing a sample on a plane sapphire produces an anisotropic strain field and anisotropy of the in-plane optical response. The chapter discusses a state-of-the-art of the physics of strain effects for the III-nitrides and presents a correlation with similar phenomena in more classic zinc-blende semiconductors. The application of a homogeneous strain in a solid changes the equilibrium position of the atoms, the crystal symmetry, and the electronic band structure and the phonon spectrum.

Chapter 5 - The Photon Bottleneck Effect in Quantum Dots

Abstract: This chapter presents experimental studies on carrier dynamics in self-assembled indium gallium arsenide/gallium arsenide (InGaAs/GaAs) quantum dots grown by the alternate supply (ALS) process and discusses their influence on lasing performance. The chapter analyzes electroluminescence and time-resolved photoluminescence data to provide recombination and relaxation lifetimes along with the carrier-relaxation processes into quantum dots. The dot's high crystal quality, which features narrow spectrum broadening and high-emission efficiency, enable to pursue the problem. Electroluminescence and time-resolved photoluminescence data are analyzed in the chapter to provide recombination and relaxation lifetimes as a function of temperature. The carrier-relaxation process into quantum dots comprises two processes: (1) the carrier relaxation from continuous energy levels into quantum-dot discrete levels and (2) the relaxation between the discrete levels inside dots. The random initial occupation (RIO) model in the analysis explains the double-exponential decay of excited levels, and electroluminescence and photoluminescence spectra that are simulated using the obtained lifetimes.

Chapter 7 - Applications of Quantum Dot to Optical Devices

Abstract: This chapter deals with the problems related to conventional technologies and discusses the direct modulation of quantum-dot lasers and the feasibility of an external modulator using quantum dots. The chapter discusses the use of quantum dots (1) as a nonlinear medium and (2) for high-density optical memories using persistent spectral hole burning. It also summarizes the roles of quantum-dot-based devices in the future of optoelectronics. The optical interconnection between boards and chips, and within chips, is becoming a research target. Other than communication and data transmission, optical data storage and optical image processing are also important research areas. Two approaches are being taken to achieve larger-capacity transmission: (1) wavelength division multiplexing (WDM) system and (2) higher data rate time-division multiplexing (TDM) system. Access networks systems—such as fiber to the home (FTTH) and fiber to the curb (FTTC)—require low power consuming lasers that provide temperature-robust performance.

Chapter 1 Polymeric and Molecular Organic Light Emitting Devices: A Comparison

Abstract: Publisher Summary This chapter focuses on light-emitting devices (LEDs) containing luminescent polymer thin films. The first LEDs-containing luminescent polymer thin films were demonstrated in 1990 (Burroughes et al., 1990), just 3 years after the reports of the demonstration of efficient molecular organic LEDs (OLEDs). Since then, the development of polymer LEDs (PLEDs) and small-molecule-based OLEDs proceeded in parallel. The two classes of devices have similar physical properties and operating characteristics between the optical and electronic properties of polymeric and molecular organic materials. The chapter describes the operating properties of PLEDs by focusing on notable differences between PLED and OLED technologies. The chapter introduces the structural and electro-optic property of polymers, describes the methods of growing thin films and emphasizes differences with molecular organic thin films. It also discusses the methods of patterning both classes of organic materials. The chapter outlines the advantages and disadvantages of both polymeric and molecular organic materials in comparison to more conventional inorganic semiconductors.

Chapter 2 Nonlinear Optics in Coupled-Quantum-Well Quasi-Molecules

Abstract: Publisher Summary This chapter presents a theoretical and experimental analysis of various nonlinear optical phenomena—second- and third-harmonic generation (SHG and THG), difference frequency mixing (DFM), multiphoton electron escape—associated with coupled quantum wells and their tunability by an applied electric field. The chapter also discusses nonlinear optics in coupled quantum-well quasi molecules. The tailoring of wave functions and energy levels using bandgap engineering and molecular beam epitaxy (MBE) has played an important role in the design of quantum semiconductor structures. Coupled quantum wells present unique opportunities for engineering new semiconductors with large optical nonlinearities associated with intersubband transitions in the infrared. These represent an excellent model system to investigate optical nonlinearities. Electrons are photoexcited to a continuum resonance above the barrier via a three-photon transition enhanced by intermediate energy levels.

Chapter 6 Perturbed Angular Correlation Studies of Defects

Abstract: Publisher Summary This chapter focuses on the perturbed angular correlation studies of defects. Radioactive probe atoms in combination with the perturbed angular correlation technique (PAC) contribute to the identification of different types of defects in different semiconductors—elemental as well as III-Vs and II-VIs. Progress in semiconductor technology is driven by progress in the knowledge and control of defects; these include intrinsic defects, such as vacancies, self-interstitials, and extrinsic defects, such as dopants and impurity atoms in these materials. One of the key problems in the control of electrical properties of semiconductors concerns the influence of the doping procedure and thermal treatment of a sample on the degree of electrical activation of the dopants. The mechanisms that cause the compensation or passivation of the dopants should be understood. Analytical techniques include electrical transport measurements, capacitance-voltage (C-V) measurements, deep-level transient spectroscopy (DLTS), and photoluminescence spectroscopy (PL). In semiconductors that have lattices with lower than cubic symmetry, the lattice site of an isolated probe atom serves as a dopant can be inferred directly from the electric field gradient produced by the charge distribution of the host lattice.

Chapter 6 - Self-Assembled Quantum Dot Lasers

Abstract: This chapter describes semiconductor lasers with self-assembled quantum dots in the active layer. It summarizes the fundamental properties of quantum dot lasers and presents InAs–GaAs quantum-dot lasers as examples. The quantum-dot laser is one of the most representative candidates for the practical application of quantum-dot structures. The fabrication process, lasing characteristics and problems to be solved are also discussed in the chapter. The chapter describes several key technologies for improving quantum-dot lasers, including closely stacked quantum-dot structures, columnar quantum-dot structures, and quantum dots emitting in long-wavelength region. The chapter concludes with a discussion of how these technologies can be applied in quantum-dot vertical cavity surface emitting laser (VCSEL).

Theory of hydrogen in GaN

Abstract: This chapter discusses the theory of hydrogen in gallium nitrite (GaN). The most commonly used acceptor is magnesium (Mg) and consequently, most investigations have focused on hydrogen interaction with Mg. The atomic geometry (AB N site) found for the Mg–H complex in GaN is very different from the well-established structure for acceptor–H complexes in other semiconductors where a BC configuration is preferred. For the gallium (Ga) vacancy, it was found that one, two, three, or four hydrogen atoms can be accommodated in the vacancy, and levels are removed from the bandgap as more hydrogens are attached. The isolated Ga vacancy is a triple acceptor; in the 3– charge state, a triply degenerate defect level about 1 eV above the valence band is fully occupied. To identify the role of hydrogen in achieving p -type GaN, the chapter analyzes the case where hydrogen is absent, corresponding to molecular-beam epitaxy (MBE) growth.

Chapter 1 Quantum Cascade Laser

Abstract: Publisher Summary This chapter discusses quantum cascade lasers. Most solid-state and gas lasers rely on narrow optical transitions connecting discrete energy levels in which population inversion is achieved by optical or electrical pumping. In contrast, semiconductor diode lasers, including quantum-well lasers, rely on transitions between energy bands in which conduction electrons and valence-band holes, injected into the active layer through a forward-biased p-n junction, radiatively recombine across the bandgap. A unipolar intersubband laser or quantum cascade laser differs in many fundamental ways from diode lasers. It relies only on one type of carrier, making electronic transitions among conduction-band states (subbands) arising from size quantization in a semiconductor heterostructure. In contrast to interband transitions, the gain linewidth depends indirectly on temperature through collision processes. In quantum cascade lasers, the gain spectrum has basically the same shape of the absorption spectrum unlike interband diode lasers.

Chapter 4 Hydrogen in III-V Nitrides

Abstract: This chapter discusses hydrogen in III–V nitrides The incorporation of acceptor impurities during metal organic chemical vapor deposition (MOCVD) growth is not sufficient; either a postgrowth processing step involving low-energy electron beam irradiation (LEEBI) or thermal annealing is required According to the behavior of hydrogen in other semiconductors, hydrogen is expected to be involved in other important processes as well The impurity introduces a level in the bandgap and the charge state depends on the occupation of that level The charge state determines the most favorable location of hydrogen in the semiconductor lattice In the positive charge state (H + , essentially a proton), hydrogen seeks out regions of high-electronic-charge density

Chapter 3 Materials in Thin Film Electroluminescent Devices

Abstract: Publisher Summary This chapter focuses on electroluminescent (EL) devices and electrical energy that is converted to visible light by a nonthermal process. The EL devices can be divided into two classes: (1) light-emitting diodes (LEDs), where the light is generated by electron-hole pairs, and (2) high-energy EL devices, where the high-energy electrons excite the emitting centers (dopant ions) to give luminescence. The EL devices are grouped in different types depending on the form of phosphors, powder vs thin film, and of the driving voltage, AC vs DC. Two of these types— namely, AC thin film electroluminescent (ACTFEL) devices and AC-driven powder EL devices—are commercially available. The current state-of-the-art of materials needed in TFEL devices are highlighted in the chapter. This includes all materials—substrates, conductors, dielectrics, and phosphors. An ACTFEL device consists of a metal–insulator–semiconductor–insulator–metal (MISIM) structure deposited on a substrate which, in a traditional case, is a transparent glass.

CHAPTER 9 - Magnetic Resonance Investigations on Group III-Nitrides

Abstract: This chapter discusses magnetic resonance investigations on group III-nitrides. The chapter reviews the identification of intrinsic and extrinsic paramagnetic defects in aluminum gallium nitride (AlGaN) by electron spin resonance (ESR) and the related techniques, optically detected magnetic resonance (ODMR), and electrically detected magnetic resonance (EDMR). To determine the electronic parameters (binding energies and concentrations), the chemical identification of the defects and conclusive answers about the local surroundings are important. Electron spin resonance is one of the most efficient techniques to provide detailed information on the electronic and atomistic structure of paramagnetic defects in semiconductors. Shifting the Fermi level from the conduction band in an n -type sample by introducing compensating centers (as a result of co-doping or by the creation of defects by particle irradiation) changes the shallow effective-mass-type donors from the occupied (paramagnetic) to the unoccupied (nonparamagnetic) charge state.

Chapter 6 CMP Consumables II: Pad

Abstract: Publisher Summary Polishing is the controlled abrasion of a surface to produce a flat specular-defect-free surface. This is generally affected by rubbing the surface to be polished with a sheet of material (a pad) in conjunction with a water-based solution containing very fine particles, which are generally inorganic oxides. Until the advent of chemical–mechanical polishing (CMP) as a potential semiconductor process technology, all commercial polishing pads were designed as analogs to earlier materials. Successful application of CMP to device processing requires a degree of control and reproducibility that were not achieved in earlier polishing applications. The composite microstructure (its composite properties and polishing performance) is largely determined by the mode of manufacture. The composite pad properties are affected by a large number of process and structural variables. One of the most significant differences between metal CMP and dielectric CMP is the effects of pad conditioning on rate for class III pads.

CHAPTER 10 – GaN and AlGaN Ultraviolet Detectors

Abstract: This chapter discusses gallium nitride (GaN) and aluminum gallium nitride (AlGaN) ultraviolet (UV) detectors. Semiconducting materials, whose resistivity may be changed by many orders of magnitude by exposing them to radiation, are a natural choice for photodetectors. They are particularly sensitive to electromagnetic radiation with photon energies exceeding their energy gaps and producing electron–hole pairs. As GaN is a direct-bandgap material with excellent transport and optical properties that is grown on sapphire, spinel, silicon, and silicon carbide substrates, this semiconductor and related materials are prime candidates for visible-blind detectors. GaN-based materials have demonstrated excellent performance potential for applications in visible-blind detectors, which may operate in harsh conditions and/or at elevated temperatures. Photons absorbed in a semiconductor may cause different types of transitions. The chapter discusses three types of transitions for UV detectors: (1) intrinsic band-to-band transitions, (2) valence band to exciton level transitions, and (3) acceptor level to conduction band transitions.

Chapter 3 – Electron Paramagnetic Resonance Studies of Hydrogen and Hydrogen-Related Defects in Crystalline Silicon

Abstract: This chapter discusses electron paramagnetic resonance studies of hydrogen and hydrogen-related defects in crystalline silicon. Hydrogen is the simple atom among the elements of the periodic table and represents the simple atomic impurity in a crystalline lattice. The phenomenon of hydrogen-enhanced diffusion of impurities in silicon most pronounced for oxygen is an exciting aspect of applied and basic semiconductor physics. These processes are evidently dependent on the ability of hydrogen to move through the crystal, which provides special motivation for the study of its diffusion mechanisms and its possible stable and metastable configurations in the silicon crystal lattice. Most of the direct experimental information concerning isolated hydrogen states in semiconductors has been obtained from muon spin rotation (μSR) and muon level-crossing resonance (μLCR) experiments on muontum—a light pseudo-isotope of hydrogen. Methods of electron paramagnetic resonance have yielded much direct information about the molecular and electronic structures of hydrogen and hydrogen-related complexes in silicon.

Chapter 2 Defect Identification Using Capacitance Spectroscopy

Abstract: Publisher Summary This chapter discusses the methods of capacitance spectroscopy and the instrumentation with which these methods are implemented The chapter also describes the properties of growth of semiconductors The technological importance of semiconductors derives from the fact that their electrical conductivity is easily modified by the addition of low concentrations of impurity atoms, which substitute for the host atoms in the lattice Substitutional impurities that introduce electronic states lying close to the bottom of the conduction band or the top of the valence band in the band gap of the semiconductor are termed “shallow donor or acceptor states” Deep defect states are often referred to as “traps,” “recombination centers,” “generation centers,” or “deep levels” The application of external perturbations—uniaxial stress or hydrostatic pressure—to modify the sample properties or the defect properties during the measurement is explained in the chapter

Chapter 1: Introduction to Hydrogen in Semiconductors II

Abstract: This chapter discusses hydrogen in semiconductors II. In plasma deposition systems, the water molecules dissociate into H and OH on electron impact and the H atom can easily diffuse into the semiconductor. The amount of hydrogen introduced into a specimen is difficult to control and depends on the condition and history of the deposition system. To study the properties of hydrogen in semiconductors, introduction of hydrogen is useful in a controllable way. Therefore, a number of hydrogenation techniques such as plasma and ion-beam hydrogenations, anneals in molecular hydrogen, and electrochemical techniques are developed. One of the most prominent properties of hydrogen is its ability to passivate deep and shallow defects. The properties of amorphous silicon improve vastly by the incorporation of hydrogen. The discovery of a variety of new phenomena related to the presence of hydrogen and the following profound impact on technology caused a veritable explosion in research activities.