X-valley influence on hot free electron absorption and optical nonlinearities at 10.6 μm in highly doped n-GaAs

A theoretical overview is given about the influence of the presence of the X-valley in highly doped n-GaAs on hot free-electron absorption and optical nonlinearities at 10.6 mum wavelength. The implications of the extension of the quantum-mechanical model from two to three valleys are discussed. For electron temperatures above 600 K the X-valley presence starts to be observed. We reveal that it is difficult to trace the individual contributions of different X-electron related inter-and intravalley absorption and relaxation phenomena and therefore we suggest to introduce an effective X-valley related deformation potential which is a weighted combination of all the X-valley contributions. We discuss how nonlinear optical experiments can be conducted to determine the LL-intervalley and this effective X-valley deformation potential.