The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

Erbium doped materials are of great interest in thin film integrated optoelectronic technology, due to their Er3+ intra-4f emission at 1.54 μm, a standard telecommunication wavelength. Er-doped dielectric thin films can be used to fabricate planar optical amplifiers or lasers that can be integrated with other devices on the same chip. Semiconductors, such as silicon, can also be doped with erbium. In this case the Er may be excited through optically or electrically generated charge carriers. Er-doped Si light-emitting diodes may find applications in Si-based optoelectronic circuits. In this article, the synthesis, characterization, and application of several different Er-doped thin film photonic materials is described. It focuses on oxide glasses (pure SiO2, phosphosilicate, borosilicate, and soda-lime glasses), ceramic thin films (Al2O3, Y2O3, LiNbO3), and amorphous and crystalline silicon, all doped with Er by ion implantation. MeV ion implantation is a technique that is ideally suited to dope these materials with Er as the ion range corresponds to the typical micron dimensions of these optical materials. The role of implantation defects, the effect of annealing, concentration dependent effects, and optical activation are discussed and compared for the various materials.

Erbium implanted thin film photonic materials

Recent developments in rare-earth doped materials for optoelectronics

Silicon photonics could enable a chip-scale platform for monolithic integration of optics and microelectronics for applications of optical interconnects in which high data streams are required in a small footprint. This paper discusses mechanisms in silicon photonics for waveguiding, modulating, light amplification, and emission. These mechanisms, together with recent advances of fabrication techniques, have enabled the demonstration of ultracompact passive and active silicon photonic components with very low loss.

Guiding, modulating, and emitting light on Silicon-challenges and opportunities

The effect of impurity coimplantation in MeV erbium‐implanted silicon is studied. A significant increase in the intensity of the 1.54‐μm Er3+ emission was observed for different coimplants. This study shows that the Er3+ emission is observed if erbium can form an impurity complex in silicon. The influence of these impurities on the Er3+ photoluminescence spectrum is demonstrated. Furthermore we show the first room‐temperature photoluminescence spectrum of erbium in crystalline silicon.

Impurity enhancement of the 1.54‐μm Er3+ luminescence in silicon

Luminescence of erbium implanted in various semiconductors such as Si, InP, GaAs, AlGaAs, GaInAsP, ZnTe and CdS is presented. The Er/sup 3+/ emission wavelength is the same for all these semiconductors with a bandgap energy greater than the intrashell transition energy of Er 4f electrons (0.805 eV). The Er/sup 3+/ emission intensity depends strongly on both the bandgap energy of the host semiconductor and the material temperature. To obtain an intense room temperature emission, a wide-gap semiconductor must be used.

Luminescence of erbium implanted in various semiconductors: IV, III-V and II-VI materials

Luminescence spectra and SIMS measurements of Er-doped silicon are presented in this paper. Luminescence was found to be stronger in Czochralski-grown Si crystals, known to contain up to 1018 cm-3 of oxygen center. Direct role played by oxygen impurities in the optical activation of the 1.54 µm luminescence was demonstrated by implanting oxygen into Er implanted layers in silicon at concentrations comparable to those of Er. Possible mechanisms of enhancement of photoluminescence are discussed.

Optical Activation of Er3+ Implanted in Silicon by Oxygen Impurities

Quantitative Cr profiles have been determined on semi‐insulating GaAs by secondary‐ion mass spectrometry (CAMECA IMS 300). It is shown that after thermal annealing (900 °C, 20 min) under Si3N4, Cr diffuses towards the GaAs surface, leaving a Cr concentration depletion zone underneath. This zone becomes conductive with a carrier concentration of n∼2×1016 cm−3. Some consequences of these findings are considered.

Chromium profiles in semi‐insulating GaAs after annealing with a Si3N4 encapsulant

Schottky contacts with barrier heights of 0.76 eV on n‐type InP and 0.65 eV on n‐type GaInAs are realized by a new surface treatment. These contacts are used as a gate for the fabrication of field‐effect transistors (FET) on these materials. Extrinsic transconductances of 100 and 7.5 mS/mm are measured on GaInAs and InP FET’s, respectively. These values are obtained without optimization of the ohmic contacts of the devices and without a gate recess.

Schottky and field‐effect transistor fabrication on InP and GaInAs

Metal‐insulator‐semiconductor (MIS) structures were produced by electron‐beam deposition of Al2O3 on InP. The electrical properties of such structures were investigated. For optimum conditions, capacitance/voltage (C/V) measurements show that the interface state density can be reduced to 1011 states cm−2 eV−1 by heat treatments. Capacitance transient measurements lead to an estimate of 2×103 cm sec−1 for the surface recombination velocity.

P. N. Favennec

Papers

Luminescence of erbium implanted in various semiconductors: IV, III-V and II-VI materials

Optical Activation of Er3+ Implanted in Silicon by Oxygen Impurities

Chromium profiles in semi‐insulating GaAs after annealing with a Si3N4 encapsulant

Schottky and field‐effect transistor fabrication on InP and GaInAs

Al/Al2O3/InP MIS structures