Electronic properties of the subsurface layer of n-GaAs single crystals (100)

In this work, the electronic properties of the near-surface layer of n-GaAs (100) single crystals grown by the solution crystallization method were investigated in order to establish a quantitative relationship between the phenomenological broadening parameter Г and the electron concentration N in n-GaAs (100) single crystals by the modulation electroreflectance spectroscopy method with the electron concentration of n-GaAs (100) N = 1021 m-3 1024 m-3 at room temperature in the energy range of 1.3 eV – 1.65 eV. The analysis of the relationship between Franz-Keldysh oscillations and electronic parameters in the high-field mode of measurements of electrical reflection spectra, in particular between the periods of Franz-Keldysh oscillations ΔEm and electro-optical energy , has been carried out. From the quantitative analysis of the electroreflection spectra for samples with an electron concentration of N = 7.5∙1022 m-3, the values of the physical parameters and parameters of the space charge region of the near-surface layer of the studied material were obtained: the energy of the electronic transition E0 (optical transition Г8v – Г6c); electro-optical energy ; the phenomenological broadening parameter Г; the surface electric field relative phase factor ψ; the energy distance from the energy of the electronic transition E0 to the extremum of the last Franz-Keldysh oscillation; the oscillation length of the wave function of a quantum-mechanical particle λFK with an effective mass μ at a given surface electric field ; the classical thickness of the enrichment layer L (); the penetration depth of the light (electromagnetic) wave d (); the penetration depth of the electric field LD ().The relationship between the energy position of the electroreflection peaks in the high-field mode of measuring electroreflection spectra Em and the electrooptic energy (f()) has been established. The empirical dependence of the phenomenological broadening parameter Г on the electron concentration N is obtained.