Infrared spectroscopy and electroreflectance in the region of fundamental optical transition E-0 of heavily doped n-GaAs (100)

Studied were the reflection spectra of dynamically chemically etched n-GaAs (100) single crystals with electron concentration of 10(18) to 5.10(18) cm(-3) in the 1.4-25 mu m range as well as the electroreflection ones in 1.3-1.6 eV range using electrolytic method. The values of physical parameters and parameters in the space charge region of subsurface layer of the investigated material have been obtained: electron concentration N, plasma frequency omega(p), relaxation time of free carriers over the pulse tau(p), energies of optical transitions E-0 (Gamma(8v)-Gamma(6c)), electrooptical energy h theta, surface electric field F-S, phenomenological broadening parameter Gamma, energy relaxation time tau, the wave function oscillation durability of quantum-mechanical particle lambda(KF) with the reduced effective mass mu at a given surface electric field F-S. The energy diagram of the chemico-dynamically etched n-GaAs (100) surface has been found to include an extreme. The presence of such extreme is explained by zero value of the electron wave function on the surface and/or the structure gettering of the free carriers.