Single and double pulse doped pseudomorphic high electron mobility transistor structures with 110-Å-thick InGaAs channel layers have been grown on InxGa1−xAs substrates (x=0.04; 0.065) and GaAs substrates. For In0.23Ga0.77As channel layers, higher electron mobilities were obtained on In0.04Ga0.96As substrates due to reduced strain. Transmission electron microscopy micrographs on a GaAs-based sample exhibited a roughened selectively doped heterojunction but no detected misfit dislocations. Pseudomorphic structures with In0.27Ga0.73As channel layers were also grown on In0.065Ga0.935As substrates with good transport and optical properties. The properties of the analogous structure grown on GaAs were severely degraded. Transmission electron microscopy micrographs on the GaAs sample showed a very rough selectively doped heterojunction with misfit dislocations.

InP-based high-electron mobility transistor (HEMT) structures have been grown containing strained In1−xAlxP Schottky layers with x=0.15–0.25. The band gaps of the strained layers in the HEMT structure were determined by photoreflectance spectroscopy. For x=0.15, Hall mobilities were comparable to those obtained in an analogous InAlAs/InGaAs structure. Lower mobilities were obtained with higher x value. Misfit dislocations were observed in plan view transmission electron microscopy for x=0.25 but not x=0.15. HEMT structures were also grown with InAsP channel layers containing moderate sheet densities. Photoluminescence measurements of the quantum well region indicated transitions to two electronic subbands. The InAs1−xPx composition was found to be weakly dependent on the phosphorus flux and uniform on 2 in. wafers.

InGaAs films have been deposited on semi-insulating InxGa1−xAs (x=0.04–0.05) substrates with improved material properties compared to similar InGaAs films grown on GaAs substrates. For near lattice matched conditions the films grown on InGaAs substrates have a smooth surface morphology compared to a dislocation-induced cross hatch morphology on GaAs substrates. The resulting film double crystal x-ray linewidths are considerably narrower. The InGaAs film photoluminescence intensity is stronger with a narrower x-ray linewidth due to the elimination of lattice mismatch dislocations. Also the Hall mobilities are higher for the films grown on InGaAs substrates.

Ga0.5In0.5P/GaAs heterojunction films were grown using a valved, three-zone phosphorus source and valved arsenic source. The design of the phosphorus source eliminates the flux bursts experienced upon valve opening with two-zone furnaces. Narrow x-ray linewidths with Pendellosung interference oscillations were observed in double crystal measurements. Chemically abrupt As/P and P/As interfaces were obtained using both valved sources. The optical band gap determined from photoluminescence was consistent with minimal ordering in the films. GaInP films were doped with silicon in the 1017 cm−3 range with good mobilities and negligible carrier freeze-out upon cooling. A GaInP(emitter)/GaAs(5×1019 cm−3 carbon doped base) heterojunction bipolar transistor exhibited a current gain of 30.

Carbon-doped GaAs films have been grown by molecular-beam epitaxy using carbon tetrabromide as the carbon source. The films were doped up to 1.3 × 1020 cm−3 with mobilities which compare favorably to beryllium-doped films. Secondary-ion mass spectrometry measurements made on these films indicate sharp transitions and negligible memory effects as well as near unity doping incorporation. Room temperature photoluminescence intensities were equivalent to comparably beryllium-doped films at 5.0 × 1019 cm−3. Photoluminescence intensities and hole concentrations were found to be dependent on both arsenic to gallium flux ratios and substrate temperature. Annealing studies on a film doped with carbon at 4.6 × 1019 cm−3 indicate good thermal stability of the carbon in the arsenic lattice site.

Inverted, pulse-doped AlGaAs/InGaAs pseudomorphic high electron mobility transistor structures were grown by molecular-beam epitaxy. Growth conditions were optimized to improve the quality of the selectively doped AlGaAs layer and to minimize dopant diffusion into the InGaAs channel. The sheet densities and mobilities of the inverted structure were found to be essentially equivalent to those obtained with the normal structure. Shubnikov–de Haas measurements exhibited strong oscillations in the magnetoresistance and plateaus in the Hall resistance. Four optical transitions from the lowest bound electron and hole quantum well states were observed in room-temperature photoluminescence spectra.

Boron-doped GaAs films grown by molecular beam epitaxy have been studied by photoluminescence. Two boron-related peaks have been observed in the spectra. The temperature dependence of these peaks is characteristic of acceptor levels, and a quantitative analysis yields activation energies of 71–72 and 188 meV. While the peak with the lower activation energy can be assigned with some confidence to the BAs0/− level, the second peak may be due to a BAs-SiGa complex rather than the BAs−/−− level.

GaAs films doped with boron in the 10(20) cm-3 range were grown by solid source molecular-beam epitaxy. Lattice contractions were observed in x-ray double crystal spectra. Substitutional boron concentrations up to 1.7 X 10(20) CM-3 were obtained with narrow x-ray linewidths and specular surface morphology. For a given boron flux, the substitutional concentration was dependent on growth temperature. P-type conductivity due to boron incorporation was measured in the films with hole concentration reaching 1 X 10(19) CM-3. The lattice contractions exhibited good thermal stability for rapid thermal anneals.

Double pulse doped AlGaAs/InGaAs pseudomorphic high electron mobility transistors have been grown by molecular-beam epitaxy on GaAs substrates. Hall mobilities in excess of 7100 cm2/V s at 300 K and 25 000 cm2/V s at 77 K are obtained with a sheet density of 3×1012 cm−2. Photoluminescence measurements indicate that two electronic subbands are occupied, and the subband energies are determined. The doping pulses are resolved in secondary ion mass spectrometry measurements. Using a double recess process, transistors have been fabricated that have produced state of the art microwave performance. At 10 GHz a 1.2 mm device has simultaneously achieved a power added efficiency of 70%, output power of 0.97 W, and gain of 10 dB.

Heterojunction bipolar transistor (HBT) structures with heavily carbon and beryllium doped base layers were grown in a conventional molecular-beam epitaxy (MBE) environment. The current gain in the carbon doped structures was reduced by enhanced bulk recombination. For a hole concentration of 5 × 1019 cm−3, the carbon concentration exceeded the hole concentration and is a likely cause of the enhanced recombination. Growth conditions were determined which minimized beryllium diffusion for HBT structures with base layers doped to 1.2 × 1020 cm−3. Lattice contractions were observed at high beryllium doping concentrations. The expected reduction in resistivity with increased beryllium base doping was obtained in the HBT structures. Using HBT structures doped with beryllium at 5 × 1019 cm−3, high-power performance was obtained at 10 GHz.

Pulse-doped pseudomorphic AlGaAs/InGaAs high electron mobility transistors with two InGaAs channels have been grown by molecular-beam epitaxy. Electrical measurements indicate that the two channels are contributing nearly equally to the conduction. The sheet density is approximately twice that of the single channel structure, and good electron mobilities are obtained. Shubnikov–de Haas measurements confirm the two dimensional transport in the structure. Direct current measurements on device structures exhibit a double peak in the transconductance, low source resistance, and a sharp pinch-off characteristic.

Carbon-doped GaAs films have been grown by solid-source molecular beam epitaxy using a graphite filament. The films were doped from 1×1015 cm−3 to 5×1019 cm−3 and the resulting mobilities are equivalent to beryllium-doped films. A slight dependence of As4/Ga flux ratio on carbon doping was observed. The use of either As2 or As4 did not significantly affect the carbon doping concentrations. Lattice contractions were observed for films doped heavily with carbon or beryllium. For a given doping concentration the contraction is more significant for carbon doping which is consistent with the smaller tetrahedral covalent radius of carbon compared to beryllium. Good agreement between observed and calculated lattice contractions with carbon doping is obtained. Annealing studies on a film doped with carbon at 5×1019 cm−3 indicate that the electrical properties and lattice contraction are quite stable.

Carbon doped GaAs and Ga0.7Al0.3As films have been grown by molecular beam epitaxy using a resistively heated graphite filament. At moderate doping levels, the effect on carbon doping of the VIII flux ratio and the nature of the arsenic species was found to be minor. The GaAs films were doped from 1X1015 to 5X1019 cm-3 and the resulting hole mobilities were equivalent to beryllium doped films. Excellent doping uniformity was obtained for 3-inch diameter films. Ga0.7Al0.3As films were also doped from 9X1017 to 3.4X1019 cm−3. For the highest carbon doped films, lattice contractions were observed which were greater than for beryllium doping. The lattice contractions were analyzed with a model using tetrahedral covalent radii.

A systematic study has been made of the photoluminescence spectra of modulation-doped strained-layer quantum wells at high electron sheet densities. Peaks associated with both the n = 1 and n = 2 electron subbands are observed, and the relative intensities are shown to be a result of the symmetry properties of the quantum wells. It is demonstrated that only the full width half maximum of the n = 2 subband peak is useful for characterizing high carrier densities.

By combining infrared absorption measurement of EL2 concentration with conventional measurement of Hall resistivity and mobility, the correlations between the total (neutral plus ionized) EL2 concentration, the net acceptor concentration, and the Hall characteristics across a semi-insulating GaAs wafer have been determined. An increase in the total EL2 concentration is found to be accompanied by a decrease in the resistivity and increase in mobility. Furthermore, there is a positive correlation between the EL2 concentration and the net acceptor concentration.