GaAsP/InGaP heterojunction bipolar transistors grown by MOCVD

Abstract

Heterojunction bipolar transistors with GaAsxP1-x bases and collectors and InyGa1-yP emitters were grown on GaAs substrates via metalorganic chemical vapor deposition (MOCVD), fabricated using conventional techniques, and electrically tested. Four different GaAsxP1-x compositions were used, ranging from = 0.825 to = 1 (GaAs), while the InyGa1-yP composition was adjusted to remain lattice-matched to the GaAsP. DC current gain close to or exceeding 100 is measured for 60 µm diameter devices of all compositions. Physical mechanisms governing base current and therefore current gain are investigated. The collector current is determined not to be affected by the barrier caused by the conduction band offset between the InGaP emitter and GaAsP base. While the collector current for the GaAs/InGaP devices is well-predicted by diffusion of electrons across the quasi-neutral base, the collector current of the GaAsP/InGaP devices exceeds this estimate by an order of magnitude. This results in higher transconductance for GaAsP/InGaP than would be estimated from known materials properties.2

High Uniformity 6-Inch InGaP Epitaxial Growth

“…Additionally, the uniformity of the growth has a significant impact on the yield, particularly for large-size epitaxial growth. It is worth noting that most studies on InGaP epitaxial growth have primarily concentrated on 2-in and 4-in sizes, with limited research conducted on the 6-in size [16][17][18][19].…”