GaAs bipolar transistors with a Ga0.5In0.5P hole barrier layer and carbon-doped base grown by MOVPE.

GaAs bipolar transistors with a 50-A-thick lattice-matched Gasub0.5Insub0.5P layer between emitter and base acting as a hole repelling potential barrier in the valence band have been fabricated from films grown by metalorganic vapor phase epitaxy (MOVPE). The 1000-A-thick base of these transistor structures was doped with carbon to 2 x 10high19 cmhighminus3 resulting in a base sheet resistance of 250 Omega. Carbon has been chosen because of its low diffusivity. Using the barrier layer as an etch stop we fabricated mesa-type broad-area devices. The output characteristics of the devices is ideal with very small offset voltages and infinite Early voltages. Common emitter current gains of up to 70 at 10high4 A/square centimetre collector current density have been obtained. The current gain is clearly higher than the one calculated for a bipolar junction transistor with the same doping profile because the base-emitter hole current is suppressed by the Gasub0.5Insub0.5P potential barrier in the valence band. It was found that the electron injection across the emitter-base junction is not affected because of the small band offset in the conduction band

A novel GaAs bipolar transistor structure with GaInP-hole injection blocking barrier.

GaAs bipolar transistors of different emitter types have been fabricated from MOCVD grown lattice matched Gasub0.5Insub0.5P/GaAs layer structures using carbon for heavy base doping (p equals 2x10high19 cmhighminus3). Besides conventional heterojunction bipolar transistors we also investigated tunneling emitter bipolar transistors having 2 and 5 nm thin GaInP layers between emitter and base, which act as a hole repelling potential barrier in the valence band. Current gains up to 115 have been obtained at collector current densities of 10high4 A/qcm even for this heavy base doping. All devices show an almost ideal output characteristics with large Early voltage and small offset voltage. From the temperature dependence of the collector current a small effective conduction band barrier at the heterointerface is determined which hardly affects electron injection into the base

AlGaInP/GaInAs/GaAs MODFET devices - candidates for optoelectronic integrated circuits

Modulation doped field effect transistors (MODFETs) with a phigh+-GaAs gate structure were fabricated from AlGaInP/GaInAs/GaAs heterostructures for the first time. Self-aligned devices with a gate length of 0.7 mym exhibit drain currents of 330 mA mmhigh-1, transconductances of 200 mS mmhigh-1 and very small gate currents below 50 nA even at gate-source voltages of - 5 V. Furthermore, large gate-drain diode breakdown voltages in excess of 30 V are observed. Short gatelength devices (0.3 mym) show a good r.f. performance with a current gain cut-off frequency of 60 GHz and a maximum frequency of oscillation of 140 GHz

OMVPE-grown AlxGa1-x0.5In0.5P/InGaAs MODFET structures - growth procedure and hall properties.

Modulation doped (AlsubxGasub1minussubx)sub0.5 Insub0.5P/InsubyGasub1minussubyAS/GaAs single quantum well structures have been grown by low pressure metal organic vapour phase epitaxy and characterized by Hall measurements and cathodoluminescence. The high conduction band offset in this structure is favourable for the fabrication of MODFET structures with high two-dimensional electron gas densities in the InsubyGasub1minusyAs channel. Electron sheet densities up to 2.75x10high12 cmminus2 have been obtained for x is equal 0.4 and y is equal 0.3 with appropriate doping. The structures have excellent Hall properties at room temperature and at 77 K. The critical interface between obtained for x equal 0.4 and y equal 0.3 with appropriate doping. The structures have excellent Hall properties at room temperature and at 77 K. The critical interface between the InGaAs channel layer and and the AlGaInP barrier layer has been improved by placing a thing AlGaAs interlayer (1.8 nm thick) between th ese two layers. This arrangement provides an abrupt interface between quantum well and interlayer and suppresses the interaction of the two-dimensional electron gas in the quantum well with the non-ideal interface between the interlayer and the AlGaInP barrier layer. Cathodoluminescence studies revealed that the mechanism of strain relaxation in these structures is distinctly different from the mechanism observed in AlGaAs/InGaAs/GaAs heterostuctures grown by molecular beam epitaxy

Direct observation by reflection high-energy electron diffraction of amorphous-to-crystalline transition in the growth of Sb on GaAs(110)

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder