A thorough discussion of the various features of the photoluminescence spectra of undoped, p‐doped and n‐doped AlxGa1−xAs (0≤x≤1) alloys is given. This review covers spectral features in the energy region ranging from the energy band gap down to ≂0.8 eV, doping densities from isolated impurities to strongly interacting impurities (heavy‐doping effects) and lattice temperatures from 2 to 300 K. The relevance of photoluminescence as a simple but very powerful characterization technique is stressed also in comparison with other experimental methods. The most recent determinations of the Al concentration dependence of some physical properties of the alloy (energy gaps, carrier effective masses, dielectric constants, phonon energies, donor and acceptor binding energies, etc.) are given. The main physical mechanisms of the radiative recombination process in semiconductors are summarized with particular emphasis on the experimental data available for AlxGa1−xAs. The effects of the nature of the band gap (direct ...

Photoluminescence of AlxGa1−xAs alloys

The metalorganic chemical vapor deposition (MOCVD) of epitaxial III‐V semiconductor alloys on III‐V substrates is reviewed in detail. The emphasis is placed on both practical and theoretical knowledge of the equipment and deposition process. The chemistry of the source alkyls and the dynamics of the transport process are discussed. The growth of the GaAs and AlxGa1−xAs systems are treated as prototypical examples (and the most studied) of the III‐V materials. Latter sections review InP, Ga1−xInxAs, and related alloys. Finally, the antimonide and the other systems are reviewed. Electronic and optical devices fabricated from MOCVD‐grown materials are used as examples of the capabilities of the growth technique.

Metalorganic chemical vapor deposition of III‐V semiconductors

We present a critical review of the strategies used in the fabrication of mismatched semiconductor heterostructures. By using simple concepts derived from the Matthews model of misfit relief, we show how the relaxation of single layers and complex structures may be analysed and predicted. These techniques allow a broad view of the processes that take place in the relaxation of strained layers. This is followed by a discussion of how the relative misfits and thicknesses of different layers in a heterostructure may influence the behaviour and distribution of dislocations in the structure. Finally, we describe the historical development and status of the experimental work and development that has been carried out in this area.

Plastic relaxation and relaxed buffer layers for semiconductor epitaxy

The characteristics of strain-modulated surface undulations formed upon epitaxial Si1−xGex alloy layers on Si

The growth of AlGaN using organometallic vapor phase epitaxy has been studied as a function of reactor pressure in a horizontal reactor. At atmospheric pressure, GaN with growth efficiency comparable to that of GaAs in the same reactor is obtained. In addition, the GaN growth efficiency changes little at different reactor pressures. These results indicate that the parasitic reaction between TMGa and NH3 is not substantial in the reactor used in this study. On the other hand, A1N growth at atmospheric pressure has not been possible. By lowering the reactor pressure below 250 Torr, A1N deposition is achieved. However, the growth efficiency decreases at higher reactor pressures and higher growth temperatures, indicating that a strong parasitic reaction occurs between TMAI and NH3. For the ternary AlGaN, lower pressure also leads to more Al incorporation. The results indicate that parasitic reactions are much more severe for TMAI+NH3 than for TMGa+NH3.

A study of parasitic reactions between NH 3 and TMGa or TMAl

Metal organic vapour phase epitaxy of indium phosphide

In-situ light scattering studies of substrate cleaning and layer nucleation in silicon MBE

In situ optical monitoring of AlGaN thickness and composition during MOVPE growth of AlGaN/GaN microwave HFETs

Optical characterisation of acceptors in doped and undoped VPE InP

Single crystal silicon wafers have been oxidised by exposure to an oxygen ambient at atmospheric pressure during RTP using an A G Associates Heatpulse 2101 Rapid Thermal Annealer. Wafers of the standard orientations used in silicon device processing , and were studied. Oxidation was carried out in the temperature range 900 to 1250°C for times of RTP from 4 to 25U seconds producing oxides up to 60nm in thickness. Oxidation rates and their orientation and temperature dependence were derived from ellipsometric measurements of oxide thickness. X-ray photoelectron spectroscopy (XPS) and infra-red absorption spectrophotometry were also employed in the oxide characterisation. Preliminary electrical characterisation of the oxides, investigated using MOS C-V analyses, showed that the interface state densities were comparable to those in conventional furnace grown oxides.

C. Pickering

Papers

Metal organic vapour phase epitaxy of indium phosphide

In-situ light scattering studies of substrate cleaning and layer nucleation in silicon MBE

In situ optical monitoring of AlGaN thickness and composition during MOVPE growth of AlGaN/GaN microwave HFETs

Optical characterisation of acceptors in doped and undoped VPE InP

Silicon Oxidation by Rapid Thermal Processing (RTP)