Control of electron density in InN by Si doping and optical properties of Si-doped InN

We have studied Si-doping profiles of InN films grown by plasma-assisted molecular-beam epitaxy and their photoluminescence (PL) properties. We confirmed experimentally that Si acts as a donor in InN. Undoped and Si-doped InN films with electron densities (n) of 1.6 x 10(18) - 1.4 x 10(19) cm(-3) showed clear n dependences of PL properties. The PL peak shifted to the higher energy side with increasing n, and the PL intensity decreased with increasing n. These were characteristics of degenerated semiconductors with a large density of defects and/or dislocations. The band-gap energy of degenerated InN films with n = 1.6 x 10(18) - 4.7 x 10(18) cm(-3) was estimated to be about 0.6 eV by assuming a nonparabolic conduction band and a constant band-renormalization effect. By taking the band-gap shrinkage of about 20 meV due to the conduction-band renormalization into account, we suggest that the band-gap energy of intrinsic InN is 0.6-0.65 eV. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.