Showing papers by "Evelyn L. Hu published in 1997"
TL;DR: A large number of novel devices have been recently demonstrated using wafer fusion to integrate materials with different lattice constants as mentioned in this paper, which have shown dramatic improvements over those which maintain a single lattice constant.
Abstract: A large number of novel devices have been recently demonstrated using wafer fusion to integrate materials with different lattice constants. In many cases, devices created using this technique have shown dramatic improvements over those which maintain a single lattice constant. We present device results and characterizations of the fused interface between several groups of materials.
151 citations
TL;DR: In this article, the design and experimental characterization of three generations of double-fused vertical-cavity lasers are described, and the result of this design evolution is the first above-room-temperature continuous-wave operation of long-wavelength VLCs.
Abstract: Detailed design and experimental characterization of three generations of double-fused vertical-cavity lasers are described. The result of this design evolution is the first above-room-temperature continuous-wave operation of long-wavelength vertical-cavity lasers. Threshold currents of 2.3 mA and yields greater than 90% have been obtained.
84 citations
TL;DR: In this article, the authors demonstrate wafer-scale integration of GaAs microlenses with vertical-cavity laser diodes and InP microlens with InGaAs photodetectors.
47 citations
TL;DR: In this article, a study of oxide-semiconductor interfaces formed by wet thermal oxidation of a thin epitaxial AlAs layer is presented, where a quantum well in close proximity to the interface is monitored before and after oxidation.
Abstract: We present a study of oxide–semiconductor interfaces formed by wet thermal oxidation of a thin epitaxial AlAs layer Photoluminescence (PL) from a quantum well in close proximity to the interface is monitored before and after oxidation The normalized PL intensity was found to decrease roughly in proportion to the degree of completeness of the oxidation The diminishing luminescence is attributed to the presence of trap states formed at the oxide–semiconductor interface formed during the oxidation process; hydrogen ion treatment is effective in the partial restoration of the luminescence In addition to the traps, the oxidation process also “disorders” the material within ∼15 nm from the semiconductor–oxide interface, as revealed by transmission electron micrographs
47 citations
TL;DR: In this paper, the authors compared the various ways in which the oxygen may be incorporated into methane/hydrogen/argon reactive ion etching of deep (>5 μm) InGaAsP/InP multilayers.
Abstract: The addition of oxygen to methane/hydrogen/argon reactive ion etching (RIE) processes can mitigate polymer deposition, and produce vertical etched sidewalls. This work contrasts the various ways in which the oxygen may be incorporated into methane/hydrogen/argon reactive ion etching of deep (>5 μm) InGaAsP/InP multilayers. Three methods are investigated: a “continuous” process in which a fixed amount of oxygen is added to methane/hydrogen/argon for the duration of the etch, a “cyclical” process in which the methane/hydrogen/argon RIE processes alternates with oxygen RIE, and a hybrid process which incorporates the advantages of both former methods. These processes are applied to the fabrication of tall (>10 μm) InGaAsP/InP quarter-wave mirrors for long-wavelength vertical-cavity lasers; the various benefits and limitations of the various approaches are discussed. It is found that the hybrid process allows formation of deeply etched structures (15 μm) with vertical profiles.
25 citations
TL;DR: In this paper, the issues connected with the application of fusion bonding technology for surface-normal optoelectronic devices (III-V semiconductors) are discussed, and InP/GaAs fusion bonding is employed in the development of long-wavelength vertical-cavity lasers.
Abstract: This paper discusses the issues connected with the application of fusion bonding technology for surface-normal optoelectronic devices (III-V semiconductors). The InP/GaAs fusion bonding technology employed in the development of long-wavelength vertical-cavity lasers is described.
19 citations
TL;DR: In this paper, it was shown that isotype heterojunctions with a perfectly flat majority or minority carrier band edge can be realized by modulation doping of arbitrary continuous alloy grading and the required impurity distribution is obtained analytically from the knowledge of the compositional grading and band structure parameters in the grading.
Abstract: We show that isotype heterojunctions with a perfectly flat majority or minority carrier band edge can be realized by modulation doping of arbitrary continuous alloy grading. The required impurity distribution is obtained analytically from the knowledge of the compositional grading and band structure parameters in the grading. This analytic relationship is exact for heterojunctions in which the grading fields are negligible in comparison with the atomic fields. We illustrate the design of flat valence-band heterojunctions for application in high-reflectivity low-resistance distributed Bragg reflectors for vertical-cavity lasers. The presented formalism enables the design of isotype heterojunctions with arbitrary band-edge profiles.
9 citations
TL;DR: In this article, the authors used a model that includes the effects of both channeling and defect diffusion, and deduced a room temperature diffusion constant of D ∼ 1 × 10−15 cm2/sec.
8 citations
TL;DR: In this article, the role of defect diffusion in InP, through experiments coupled with simulations, is delineated and an estimate of the defect diffusion constant is obtained and it is found to be in...
Abstract: Channeling of incident ions and radiation-enhanced diffusion of the ion-created defects have been shown to be major components of the ion damage profile. Our earlier results showed a deeper damage profile in InP, compared to GaAs, when subjected to the same ion bombardment conditions. Computer simulations demonstrated that this can partially be attributed to the greater ion channeling range in InP. In this article the role of defect diffusion in InP, through experiments coupled with simulations, is delineated. The multiple quantum well (MQW) probe technique is used to determine the amount of damage by measuring the change in low temperature photoluminescence of quantum wells before and after argon ion bombardment. A blocking superlattice is added to the MQW heterostructure and is proven effective in preventing damage from propagating into the material below it. By correlating the experimental results with computer modeling, an estimate of the defect diffusion constant is obtained and it is found to be in ...
8 citations
TL;DR: In this article, a thin layer (∼200 A) of annealed low-temperature GaAs (LT-GaAs) was used to reduce ion damage that would occur during the formation of a dry-etch gate recess of a high electron mobility transistor.
Abstract: We have successfully used a thin layer (∼200 A) of annealed low-temperature GaAs (LT-GaAs) to reduce ion damage that would occur during the formation of a dry-etch gate recess of a high electron mobility transistor. Compared to structures without an ion damage blocking layer, the devices with a thin layer of LT-GaAs are more robust against ion damage. This is important for the application of ion-assisted processing to the fabrication of electronic devices, such as dry etching used to achieve gate recessing.
8 citations
TL;DR: In this article, the initial stages of wet AlAs oxidation using D2O as the oxidant were investigated using Auger electron spectroscopy and temperature-programmed desorption, and it was shown that molecularly adsorbed water on AlAs(001) has two competing reaction pathways available: either desorcption back into the gas phase, or dissociation resulting in aluminum oxide, aluminum hydroxide, and arsenic hydride.
Abstract: The initial stages of oxidation of AlAs(001) (using D2O as the oxidant) have been investigated using Auger electron spectroscopy and temperature-programmed desorption. We have found that molecularly adsorbed water on AlAs(001) has two competing reaction pathways available: either desorption back into the gas phase, or dissociation resulting in aluminum oxide, aluminum hydroxide, and arsenic hydride. Recombination of the arsenic hydride produces arsine, which desorbs and depletes arsenic within the oxide film, a process which is shown to enhance the oxide growth. By identifying the various reaction steps that occur (with annealing) after the low-temperature adsorption of water on AlAs(001), we are able to propose a mechanism for the initial stages of wet AlAs oxidation.
TL;DR: In this article, an epitaxial AlGaAs etch stop layer between the GaAs top layer and substrate and then etching with Cl 2 O 2 was used to focus a 50 micron x-ray beam to ∼5 microns for Si structures.
TL;DR: In this paper, the initial stages of wet AlAs oxidation were investigated using Auger electron spectroscopy, temperature-programmed desorption and high-resolution electron energy-loss spectrometric analysis.
07 Dec 1997
TL;DR: The discovery of an oxide created by the wet thermal oxidation of Al/sub x/Ga/sub 1-x/As compounds has created excitement in the general field of wet thermal oxidization of Al bearing compound semiconductor as mentioned in this paper.
Abstract: The discovery of an oxide created by the wet thermal oxidation of Al/sub x/Ga/sub 1-x/As compounds has created excitement in the general field of wet thermal oxidation of Al bearing compound semiconductor We have investigated the use of these oxides for a variety of electronic applications in III-V technology We have demonstrated oxide based MISFETs and GaAs On Insulator (GOI) technologies for high efficiency electronics as well as novel applications such as current aperturing for RTD's and vertical transistors
TL;DR: In this article, the effects of changes in ion dose rate and the application of laser radiation on the diffusion of dry-etch damage observed from experiments has been further characterized with Schottky diodes and deep level transient spectroscopy (DLTS) measurements.
Abstract: Radiation-enhanced diffusion of dry-etch damage observed from experiments has been further characterized with Schottky diodes and deep level transient spectroscopy (DLTS) measurements. The use of DLTS spectra to monitor the effects of changes in ion dose rate and the application of laser radiation shows that the ion-induced defects having high diffusivities during ion-assisted processes are basically associated with the components of primary point defects, such as interstitials and vacancies. The properties of ion-induced traps obtained from DLTS measurements may provide us with some information to refine our model on the low-energy ion-induced damage.
18 May 1997
TL;DR: In this paper, the authors compare free-space and plasma-based collider designs and estimate the severity of these problems free space and plasma based colliders with respect to their interaction point requirements for short-wavelength accelerators.
Abstract: ters of the accelerated beam and therefore of the any potential accelerating system. The paper will build on previous analysis of the interaction point requirements for short wavelength accelerators.’ The luminosity requirement is fixed by desired event rate and (small) cross sections at these energies. Both average power and high gradient requirements favor the short wavelength, laser-driven systems. Beam quality constraints, imposed by the requirement that the beams collide in very small (typically of order a few Angstroms) spot sizes, demand a detailed understanding and control of the accelerator system. The accelerated beam quality can deteriorate through a variety of mechanisms. In a free-space laser accelerator the bunch must propagate through a series of small structures and will leave wakefields behind it. For example, in a laserplasma accelerator, particle focusing is provided by the transverse components of the plasma wake. The strength of the accelerating field determines the transverse focusing strength and thereby the level to which stray fields need to be controlled. These undesirable fields can originate from laser-plasma instabilities, density inhomogeneities, laser mismatch or jitter, etc. The electron beam in the plasma or in small structures will generate wakes. These effects are less pronounced in a plasma than in free-space laser accelerators since the plasma accelerator has a longer wavelength (and hence wider transverse dimensions) and the plasma is, ideally, homogeneous in the longitudinal direction. We estimate and compare the severity of these problems free-space and plasma-based collider designs.
14 Jul 1997
11 Aug 1997
TL;DR: In this article, the design of InP-InGaAsP MQW vertical cavity lasers to achieve high temperature operation was discussed and it was concluded that the key to such design is the reduction of round trip cavity loss.
Abstract: Summary form only given In this presentation we will focus on the design of InP-InGaAsP MQW vertical cavity lasers to achieve high temperature operation We have concluded that the key to such design is the reduction of round trip cavity loss We show the low loss double-fused laterally oxidized structure used in our work This structure allows for high mirror reflectivities using GaAs based mirrors reducing the necessary gain at threshold
04 Apr 1997
TL;DR: In this paper, a 15 micrometer vertical cavity laser with two fused Al(Ga)As/GaAs mirrors with a strain-compensated InGaAsP/InP active region was used for current confinement.
Abstract: In this work we report on 64 degree celsius continuous-wave operation of a 15 micrometer vertical cavity laser This laser consists of two fused Al(Ga)As/GaAs mirrors with a strain-compensated InGaAsP/InP active region Selective lateral oxidation is used for current confinement Minimum room temperature threshold current is as low as 08 mA, and maximum cw output power is as high as 1 mW at 15 degrees Celsius Pulsed operation is achieved up to 100 degrees Celsius© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only