M. Merrick

Photoluminescence spectroscopy of bandgap reduction in dilute InNAs alloys

Photoluminescence (PL) has been observed from dilute InNxAs1–x epilayers grown by molecular-beam epitaxy. The PL spectra unambiguously show band gap reduction with increasing N content. The variation of the PL spectra with temperature is indicative of carrier detrapping from localized to extended states as the temperature is increased. The redshift of the free exciton PL peak with increasing N content and temperature is reproduced by the band anticrossing model, implemented via a (5×5) k·p Hamiltonian.

Suppression of D'yakonov-Perel spin relaxation in InAs and InSb by n-type doping at 300 K

We have made direct pump-probe measurements of spin lifetimes in intrinsic and degenerate n-InAs at 300 K. In particular, we measure remarkably long spin lifetimes (τs∼1.6 ns) for near-degenerate epilayers of n-InAs. For intrinsic material, we determine τs∼20 ps, in agreement with other workers. There are two main models that have been invoked for describing spin relaxation in narrow-gap semiconductors: the D’yakonov–Perel (DP) model and the Elliott–Yafet (EY) model. For intrinsic material, the DP model is believed to dominate in III–V materials above 77 K, in agreement with our results. We show that in the presence of strong n-type doping, the DP relaxation is suppressed both by the degeneracy condition and by electron–electron scattering, and that the EY model then dominates for the n-type material. We show that this same process is also responsible for a hitherto unexplained lengthening of τs with n-type doping in our earlier measurements of n-InSb.

Bandgap Bowing In InSb1−xNx Investigated With A New Fourier Transform Modulated Spectroscopy Technique For The Mid‐Infrared

Using an FTIR‐based photo‐modulated transmission spectroscopic technique a red‐shift in bandgap has been observed at room temperature for an InSb1−xNx ternary alloy, relative to binary InSb, and determined to be approximately around 16meV (10%), corresponding to an incorporated nitrogen concentration of 0.1%.