Analytical study of high absorption region of the absorption edge of a-Si:H using nonlinear regression method

This research is concerned with the re-analysis of optical data (the imaginary part of the dielectric function as a function of photon energy E) of a-Si:H films prepared by Jackson et al. and Ferlauto et al. through using nonlinear regression fitting we estimated the optical energy gap and the deviation from the Tauc model by considering the parameter of energy photon-dependence of the momentum matrix element of the p as a free parameter by assuming that density of states distribution to be a square root function. It is observed for films prepared by Jackson et al. that the value of the parameter p for the photon energy range is is close to the value assumed by the Cody model and the optical gap energy is which is also close to the value of the Cody gap of these films. While for the films prepared by Ferlauto et al. the value of the parameter is equal to and .

Gain Calculation in a Quantum Well Laser Simulator Using an Eight Band k.p Model

Effects of non-parabolicity and band-warping of the energy dispersion are entered in a quantum well laser simulator (MINILASE-II), which self-consistently solves Schödinger's equation, Poisson's equation, the drift diffusion equations, and the photon rate equations. An eight band k.p model is used to determine the electronic band structure for a strained-layer In.2Ga.8As/Al.1Ga.9As system. The k.p calculation is performed independently of the laser simulator, and exported to MINILASE-II in the form of a density of states and an energydependent averaged momentum matrix element. The results obtained for the gain and modulation response are compared to those obtained from a parabolic band model with a constant matrix element.