The diffusion of Be from buried Be-doped layers in GaInAs has been studied for temperatures between 600 and 700 °C. An interstitial-substitutional model is proposed for the diffusion mechanism, which is dependent on growth conditions and consistent with the data presented. Under growth conditions where Be transport is minimized GaInAs junction field-effect transistors have been produced with transconductances in excess of 200 mS mm−1 for a 1-μm gate length.

Photoluminescence studies of Ga, .In,As/Al, ,In,As quantum wells nominally lattice matched to InP are reported. The photoluminescence from two samples each having six quantum wells of thicknesses ranging from about 6 to 122 A is studied in detail. The main emission peak associated with each qu3ntum well is attributed to excitonic recombination. The emission from the 6 A quantum well at 897.3 nm is found to have a peak width of only 18 meV at 4.2 K. Temperature dependence studies show that at 4.2 K the excitons are localised at potential fluctuations in the quantum wells. Impurity-related emission is also observed from some of the quantum wells.

Degenerate electron-hole plasmas have been produced in the quantum wells of GalnAs/AllnAs MOW systems using 100 PS pulses from a Q-switched, mode-locked Nd-YAG laser. Photoconductivity parallel to the layers showed band-filling effects, and good exponential decays were observed over several orders of magnitude of carrier density. For a 50 well system with 50 8, wells and 100 8, barriers the recombination time constant was 3.6k0.2 ns between 300 K and 150 K, rising to 7 n s at 40 K. There was no indication of Auger processes, implying that the Auger coefficient was less than lO-30 cm6 S-', which is much smaller than the reported values. The intensity of light at the onset of band filling reduced linearly with reducing temperature between 300 K and 150 K following a trend expected from the temperature dependence of the band gap. The initial well photoconductivity produced by a given light intensity reduced with reducing temperature. The electron mobility in the electron-hole plasma was about 400 cm2 V" S-' . No change with carrier density was observed. Below 40 K short time constant components tend to dominate the decay and the photoconductivity becomes noisy. In the case of a 20wellsamplethesignalwasheavilyinfluenced byphotoconductivityinthesemiinsulating InP substrate. It is pointed out that band filling allows a distinction to be made between well and substrate/cladding photoconductivities.

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We have measured the room-temperature intensity dependence of the optical transmission of an In(0.53)Ga(0.47)As/In(0.52)Al(0.48)As multiple-quantum-well structure from 1.5 to 1.7 microm. The absorption is calculated from the transmission by taking into account the wavelength dependence of the reflection coefficients. An intensityof 15 kW cm(-2) is required to reduce the absorption by one half for excitation at the edge of the 1H-lC transition absorption band. For intensities exceeding 10(7) W cm(-2), complete saturation of the absorption is observed. A theoretical model is described that fits the intensity dependence of the absorption right upto saturation at two wavelengths and predicts a carrier lifetime of 0.75 nsec, which has been confirmed by independent measurements.