High efficient terahertz emission from InN surfaces

Terahertz radiation was measured from InN and compared to p-InAs excited by femtosecond optical pulses at 1060 and 800 mn. At 800 mn, atomically smooth InN with low background electron concentration exhibit higher THz emission than the highly effective material p-InAs. The higher THz emission efficiency of InN is caused by the absences of any intervalley scattering, which in the case of InAs increases the effective mass of the photo generated electrons and, thus, reduces the Dember field, which is responsible for THz emission. Consequently, InN is a promising material for THz emission; however, further improvement of the material quality (surface roughness and carrier concentration) is needed. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.