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In this report, we present data on an InGaAs/GaAs strained single quantum well laser with the lowest reported threshold current density to date, namely 44 A cm−2 for a 3 mm cavity length. This was grown by solid-source molecular-beam epitaxy with the arsenic dimer, As2. The structure is that of a graded-index, separate-confinement heterostructure with a single strained InGaAs quantum well, sandwiched between GaAs barrier layers and AlGaAs cladding layers. The wavelength of the lasers was around 985 nm, and the internal efficiency and losses were 69% and 0.70 cm−1, respectively. In addition, data on the uniformity of our lasers, which are grown on rotating 2 in substrates (1 in = 2.54 cm), show drops in photoluminescence emission wavelength and layer thickness of less than 4 nm and 4%, respectively, from the centre to the edge of the wafer and very little compositional change.

The migration of indium on patterned substrates during MBE growth is found to be strongly dependent upon the arsenic species used. InGaAs-GaAs SQW lasers grown on narrow mesas using AS/sub 4/ exhibited 70-meV redshifts, while those grown using As/sub 2/ showed only small redshifts.

Semiconductor lasers emitting at 1.3 /spl mu/m and 1.55 /spl mu/m wavelengths are of particular interest because of their application in optical fibre communication systems. In this work, we investigate for the first time the process of indium migration during the growth of InGaAs-InAlAs single quantum wells grown by MBE on patterned InP substrates for the fabrication of long wavelength integrated optoelectronic devices.

Numerical modeling of inversion-layer (IL) solar cells is described. The steady-state continuity equations are solved for both electrons and holes. A novel integrated recombination technique is applied to accurately find the one-dimensional current flow. Two-dimensional resistive and grid geometry effects are modeled to predict the output current-voltage curve for the cell. Modeled results are in excellent agreement with those measured for a real cell. The model is used to investigate the operation of IL cells and to determine how their performance can be improved through process changes. Practical AM1 efficiencies up to 17 percent are predicted and a theoretical maximum efficiency of 21 percent is calculated. Many of the modeling techniques and results can be applied to other solar-cell structures.

A recently developed induced junction solar cell (1) has been electrically characterized to determine its performance and how it may be improved through process optimization. Prototype cells are described in terms of their structure, fabrication and advantages over diffused junction cells. Several devices were subjected to ionizing radiation in the form of low energy electrons and x-rays. The novel methods used for electron irradiation and measuring its effect on the cells are described. While large variations in oxide charge and flatband voltage were observed, only minimal effects on the cells photovoltaic behaviour resulted. The radiation induced changes were found to be annealable.