Germanium- and zinc-doped p-type InAsSb single crystals with a cutoff wavelength of 12.5 μm

We grew germanium (Ge)- and zinc (Zn)-doped p-type InAs0.04Sb0.96 epilayers with a cutoff wavelength of 12.5 mu m on n-InAs substrates by melt epitaxy (ME), and undertook a study of the properties of Ge-doped long-wavelength p-InAsSb epilayers. The quality of the epilayers was evaluated by transmittance, electroprobe microanalysis (EPMA) and Van der Pauw measurements. The results showed that the cutoff wavelength of the InAsSb epilayers with different levels of Ge doping showed no significant changes when the composition of the epilayers was kept constant. The Ge distribution, both on the surface and along the growth direction of the epilayer, is rather homogeneous. A maximum hole mobility of 1120 cm(2)/Vs with a carrier density of +9.18 x 10(16) cm(-3) at 77 K was achieved in a Ge-doped p-InAsSb epilayer. However, in the case of a Zn-doped epilayer, a hole mobility of 860 cm(2)/Vs with a carrier density of +2.48 x 10(17) cm(-3) was obtained at 77 K.