Annealing effects on heavily carbon-doped GaAs

Abstract

The hole concentrations and lattice mismatch with the GaAs substrate of heavily carbon-doped epilayers (4.7×1019 and 9.8×1019 cm−3) were increased and the mobilities were decreased as compared with the as-grown samples by rapid thermal annealing silicon nitride capped samples at temperatures from 500 to 900 °C. However, for the more heavily doped sample, the hole concentration, mobility, and lattice mismatch decreased with increasing annealing temperature for annealing temperatures higher than 700 °C, but the hole concentration and lattice mismatch were still larger than those of the as-grown samples. Secondary ion mass spectroscopy results showed that annealing produced no change in the C concentration or distribution, but the hydrogen concentration decreased. Cross-sectional transmission electron microscopy indicated that no mismatch dislocations formed at the interface.

Layer Disordering and Carrier Concentration in Heavily Carbon-Doped AlGaAs/GaAs Superlattices

“…(13) and (14) and the thermal equilibrium PAs 4 values given by Arthur [20] for GaAs crystals with compositions at the thermodynamically allowed Ga-rich limits. Equation (15) approximately fits the present Ds(Ga-rich) data.…”

“…Using AlAs/GaAs SL, a few studies on the effect of carbon doping on Al-Ga interdiffusion have been conducted, but the results are not consistent [3][4][5]. The CA, diffusivity values have been measured [1,[5][6][7][8], and hole concentrations in carbon-doped GaAs and SL crystals have been reported to decrease when annealed at temperatures higher than -600°C [6,7,[9][10][11][12][13][14][15]. However, the CA s diffusion and hole reduction mechanisms remain unclear.…”

Influence of growth parameters on the composition and impurity levels of intrinsically carbon doped AlxGa1−xAs

“…Several papers report that hydrogen deactivates the incorporated carbon so that the hole concentration is given by [C]À[H] [36][37][38]. The open circles in Fig.…”

Carbon doping of III-V compound semiconductors

“…(Enquist, 1992) Transmission electron microscopy (TEM) of annealed epitaxial layers which were heavily doped with C and show a significant reduction of free carrier concentration showed no evidence of the formation of dislocations. (Han, et al, 1992) (Han, et al, 1992) Although dislocations were not seen with TEM the strain was relieved in the epitaxial layers following annealing.…”

“…(Han, et al, 1992) It is further suggested that these dislocations have electrical character (donor) which compensate the C acceptors. It is unlikely that dislocations would exist in heavily C doped GaAs and that they would create a sufficient concentration of electrically active donors to compensate C acceptor cocentrations greater than 1 Q20 cm-3.…”