Laser-induced modulation of optical band-gap parameters in the III–V-type semiconductors from the density-of-state (DOS) calculations

Abstract

Optical band gap ($E_{\mathrm{g}0}$) is a parameter of paramount importance in describing various transport and opto-electronic properties of the III–V-type low band-gap semiconductors. In the present communication, an attempt has been made to develop an energy–momentum ($E{-}{\bar{k}}$) dispersion relation for studying the density-of-state (DOS) and band-gap-related parameters. The external laser excitation has been treated as a perturbation. It has been shown theoretically that due to such excitation with different intensity (I) and wavelength $(\lambda )$, the band edge of the conduction band (CB) of the III–V compound semiconductors moves vertically upward, indicating laser modulation (increase) of $E_{\mathrm {g}0}$ and related parameters compared to those of the normal ones (unperturbed). Therefore, in the presence of light, the original CB edge forms a pseudo-CB edge above the unperturbed CB edge in the forbidden band (FB) zone. This new development of the ($E{-}{\bar{k}}$) relationship has also been extended for the estimation of exact optical effective mass (OPEM) of an electron in some III–V compound semiconductors. The OPEM variation with carrier concentration showed a continuous decreasing nature, while the corresponding variation of electron effective mass (EEM) (without laser excitation) exhibited an increasing trend. The present theoretical results would be important for the deeper understanding of the variation of OPEM with I and $\lambda$. The observed new results will also be beneficial for studying laser-induced effects in semiconductor heterostructures with different applications in optoelectronic devices.