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

GaAs-Bipolartransistoren mit Ga0.5In0.5P-Schicht als Löcherbarriere und kohlenstoffdotierter Basis, gezüchtet mit MOVPE
: Bachem, K.H.; Lauterbach, T.; Pletschen, W.

IEEE transactions on electron devices 39 (1992), No.4, pp.753-756 : Abb.,Lit.
ISSN: 0018-9383
Journal Article
Fraunhofer IAF ()
bipolar transistor; Bipolartransistor; C-Dotierung; carbon doping; GaAs; GaInP; HBT; MOVPE; TEBT

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.