Molecular beam deposition of low-resistance polycrystalline InAs

We report low-resistance Si-doped polycrystalline InAs (poly-InAs:Si) using molecular beam deposition. We believe this to be the first report of low resistance in poly-InAs. The poly-InAs:Si was deposited using conventional molecular beam epitaxy (MBE) onto SiN_x coated GaAs substrates at various growth temperatures and deposition rates. Poly-InAs samples with thicknesses of 2000 Å and 1000 Å were grown for Hall and TLM measurements, respectively. We have observed electron concentrations from 8.8×10¹⁸ to 1.5×10¹⁹ cm^-3 and respective mobilities from 886 to 441 cm²/Vs. This range of values suggests that the poly-InAs:Si has a doping-mobility product, and hence bulk conductivity, that is only 3-4 times lower than that of similarly doped InGaAs lattice-matched to InP. The typical bulk resistivity determined by TLM measurements is approximately 1.4×10^-3 Ω-cm. Contact resistance to the poly-InAs with a Ti/Pt/Au metal stack less than 1.6×10^-7 Ω-cm². The combined low contact access resistance and low junction capacitance found in poly-InAs:Si may be useful in a variety of III-V device applications.