The effects of the magnitude of the modulation field on electroreflectance spectroscopy of undoped-n+ type doped GaAs

Abstract

The electroreflectance (ER) spectra of an undoped-n+ type doped GaAs has been measured at various amplitudes of modulating fields (δF). Many Franz–Keldysh oscillations were observed above the band gap energy, thus enabling the electric field (F) in the undoped layer to be determined. The F is obtained by applying fast Fourier transformation to the ER spectra. When δF is small, the power spectrum can be clearly resolved into two peaks, which corresponds to heavy- and light-hole transitions. When δF is less than ∼1/8 of the built-in field (Fbi∼77 420 V/cm), the F deduced from the ER is almost independent of δF. However, when larger than this, F is increased with δF. Also, when δF is increased to larger than ∼1/8 of Fbi, a shoulder appears on the right side of the heavy-hole peak of the power spectrum. The separation between the main peak and the shoulder of the heavy-hole peak becomes wider as δF becomes larger.

A complex Fourier transformation study of the contactless electroreflectance of an undoped-n+GaAs structure

“…This approach neglects the light hole's contribution and the difference between the two non-flat electric fields. Recently, Fourier transformation (FT) has been used to analyse FKOs measured by PR [8][9][10][11], ER [12,13], CER [10] and piezoreflectance (PzR) [14]. Jin et al [15] utilized complex Fourier transformation (CFT), including real part, imaginary part and modulus of FT, to study FKOs in the UN + structure in PR experiments.…”