Carbon doping and lattice contraction of GaAs films grown by conventional molecular beam epitaxy

Abstract

Carbon-doped GaAs films have been grown by solid-source molecular beam epitaxy using a graphite filament. The films were doped from 1×1015 cm−3 to 5×1019 cm−3 and the resulting mobilities are equivalent to beryllium-doped films. A slight dependence of As4/Ga flux ratio on carbon doping was observed. The use of either As2 or As4 did not significantly affect the carbon doping concentrations. Lattice contractions were observed for films doped heavily with carbon or beryllium. For a given doping concentration the contraction is more significant for carbon doping which is consistent with the smaller tetrahedral covalent radius of carbon compared to beryllium. Good agreement between observed and calculated lattice contractions with carbon doping is obtained. Annealing studies on a film doped with carbon at 5×1019 cm−3 indicate that the electrical properties and lattice contraction are quite stable.

Role of InAs and GaAs terminated heterointerfaces at source/channel on the mixed As-Sb staggered gap tunnel field effect transistor structures grown by molecular beam epitaxy

“…It has been well established that for C doped III-V materials beyond the doping level of 1 Â 10 19 /cm 3 , substitutional carbon causes the III-V host lattice to contract due to its small tetrahedral covalent radius (0.77 Å ). Lattice mismatch due to lattice contraction by heavily doped C atom has already been reported and calculated in GaAs, 34,35 GaSb, 36 InGaAs, 37 and AlGaAs 35 material systems. In our case, similar lattice contraction in GaAs 0.35 Sb 0.65 was also observed at the doping level of 5 Â 10 19 /cm 3 .…”

Carbon doping of III-V compound semiconductors

“…In the heavily doped sample, the carrier concentration increased slightly for annealing temperatures up to 600°C. At higher temperatures the hole concentration and the mobility both decreased as shown in (Hoke, et al, 1991) …”

“…The strain can be measured by X-ray diffraction and several groups have found that the lattice constant is reduced in accordance to Vegard's law. (Hoke, et al, 1991) The results from annealing experiments reported in the literature are tabulated in Table 2.2. Two detailed studies will be highlighted.…”

“…(Giannini, et al, 1992) Resistively heated graphite filaments have been • used as a source of C in conventional MBE systems. (Malik, et al, 1988) (Hoke, et al, 1991) In this case, the evaporation rate and hence the incorporation rate of C is determined by the filament temperature. Doping levels as high as 1 x 1020 cm-3 with 11 abrupt doping profiles have been achieved.…”

Growth aspects of AlGaAs/GaAs tunnel diodes for multijunction solar cells

“…In particular we compare the XRD experimental results with the lattice contraction model proposed by W.E.Hoke at al [16]. For sake of completeness we report the lattice contraction formula, which describes a linear increase of the lattice parameter variation in function of the carbon incorporation, that is:…”