Iodine and carbon tetrabromide use in solid source molecular beam epitaxy

Abstract

Articles you may be interested inStudy of direct current characteristics of carbon-doped GaInP/GaAs heterojunction bipolar transistor grown by solid source molecular beam epitaxy Properties of carbon-doped low-temperature GaAs and InP grown by solid-source molecular-beam epitaxy using CBr 4Growth of carbon doping Ga 0.47 In 0.53 As using CBr 4 by gas source molecular beam epitaxy for InP/InGaAs heterojunction bipolar transistor applications Molar fraction and substrate orientation effects on carbon doping in InGaAs grown by solid source molecular beam epitaxy using carbon tetrabromideWe have studied CBr 4 doping of GaAs and In 0.53 Ga 0.47 As up to 2ϫ10 20 /cm 3 , of In x Ga 1Ϫx As across the composition range from xϭ0 to xϭ1, and of GaAs and In 0.53 Ga 0.47 As on the (211)A, (311)A, (511)A, (511)B, (311)B, and (211)B planes. These data show little evidence of self-compensation in C-doped GaAs, although carbon incorporation is more efficient on the Ga-rich (n11)A surfaces. In 0.53 Ga 0.47 As shows a similar dependence of carbon incorporation on surface orientation, and also exhibits self-compensation on the As-rich (n11)B surfaces and at In molar fractions x greater than about 0.7. We have made heterojunction bipolar transistors ͑HBTs͒ with abrupt emitter-base junctions and GaAs base layers doped to 1ϫ10 20 /cm 3 which have useful dc current gains, and have also used in situ iodine etching for regrowth over patterned subcollectors to make operating HBTs designed for reduced base-collector capacitance. Despite using CBr 4 nearly exclusively as our p-type dopant in solid-source molecular beam epitaxy for more than five years and iodine for more than two years, we have observed no persistant degradation in doped or undoped material quality as measured by photoluminescence intensity, carrier mobility, or npn heterojunction bipolar transistor HBT current gain. Photoluminescence intensity and 77 K carrier mobility have gradually improved coincident with the introduction and continued use of iodine in our system, although there is no direct evidence of causality.

Growth and characterization of carbon doped GaAs- and InP- based heterojunction bipolar transistors

“…The first carbon doped (C-doped) GaAs grown by SSMBE using carbon tetrabromide (CBr4> as p-type dopant precursor was reported in 1993 [15]. After that, the memory effect [16], substrate orientation dependence [17], iodine incorporation [18], and low temperature growth performance [19] of the C-doped materials have been reported. However, although there are reports on the realization of C-doped…”

“…In 1993, the current gain of 2690 was reported for GalnP/GaAs HBT with a 1000 A GaAs base layer (Be-doped, 5xl0 18 cm" 3 ) grown by MOMBE [79]. The highest /, and /", of C-doped GalnP/GaAs HBTs reported were 156 GHz and GHz, respectively, in 1998, that were grown by GSMBE [80].…”

“…Table 6.1 shows the layer structure of the HBT. The epitaxial layers consists of 5200 A n = 4xl0 18 cm" GaAs sub-collector, a 200 A GalnP which is inserted in the sub-collector to serve as etch stop layer, a 6000 A n = lxlO 16 cm" 3 GaAs collector, a 520 A p = 5xl0 19 cm" 3 GaAs base layer, a 500 A n = 3xl0 17 cm" 3 Gao.51Ino.49P…”

“…emitter, a 1200 A n = 4xl0 18 cm" 3 GaAs cap, a 400 A n = lxlO 19 cm" 3 In x Gai_ x As graded cap layer (x=0-0.6), and a 400 A n = lxlO 19 cm" 3 Ino.6Gao.4As ohmic contact layer. GalnP.…”

“…The actual doping profile was measured using SIMS measurement. GaAs n = 4x10 18 cm" 3 1200A GalnPn = 3x10"cm' J 500A…”