Carbon Doping of InGaAs for Device Applications

Abstract

Carbon has gained wide acceptance as a p-type dopant for GaAs-based device structures due to its low atomic diffusivity. Carbon doping of InGaAs, however, is complicated by the amphoteric nature of C and difficulty in incorporating C efficiently during epitaxial growth. We have achieved hole concentrations as high as 7x1019 cm−3 in CC14-doped InGaAs grown at low temperature by MOCVD. Growth-related issues include the effect of CCl4 on the alloy composition due to etching during growth, and the incorporation of hydrogen, which passivates the C acceptor and reduces the hole concentration during growth and during the post-growth cool-down. The effect of H passivation on minority carrier transport has been characterized by the zero-field time-of-flight technique. High frequency InP/InGaAs HBTs with a C-doped base have been demonstrated with ft = 62 GHz and fmax = 42 GHz, which is comparable to the best performance reported for MOCVD-grown InP/InGaAs HBTs.

Carbon-doped InP∕In0.53Ga0.47As single and double heterojunction bipolar transistors grown by solid-source molecular-beam epitaxy

“…Figure 1 shows the hole mobility at room temperature for carbon-doped InGaAs layers grown by SSMBE as function of net hole concentration. As-grown data of C-doped InGaAs grown by GSMBE, 5 MOCVD, 16 and SSMBE 17 reported by other workers is included for comparison. The hole mobilities in our SSMBE-grown C-doped InGaAs layers are comparable to those grown by GSMBE, MOCVD, and by other groups.…”

Carbon doping of Ga0.47In0.53As using carbontetrabromide by metalorganic molecular beam epitaxy for InP-based heterostructure bipolar transistor devices

“…Depending on the growth method a substantial amount of passivation of C acceptors has been observed. 8 Postgrowth annealing with no H present at temperatures around 450°C for 5 min reactivates a majority of the passivated carbon by diffusing the H out from the lattice. In our experiments Hall and secondary ion mass spectroscopy ͑SIMS͒ data were used to evaluate the bulk doped layers.…”

“…This has also been reported in MOCVD grown material. 8 In HBTs under high bias conditions migration of the base dopant into the emitter over time is a serious concern. This will substantially shift the turn on voltage, V BE , for the emitter junction and degrade the gain of the device.…”