Browsing by Author "Sung, YG"

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Effect of modulating field on photoreflectance simulated by electroreflectance
(1999-04-01)
Chiou, SJ
;
Sung, YG
;
Wang, DP
;
Huang, KF
;
Huang, TC
Photoreflectance (PR) of surface-intrinsic- n(+) (s-i-n(+)) type doped GaAs has been simulated by electroreflectance (ER). The simulated spectra of the s-i-n(+) sample have exhibited many Franz-Keldysh oscillations, which enable the electric field (F) to be determined. It is known that F's determined from PR are subjected to photovoltaic effect and the measured F is close to F-bi -delta F/2 when the modulating field, delta F much less than F-bi, where F-bi is the built- in field of the sample and delta F is the modulating field. In this work, we have investigated the relation between the measured F and delta F not only for the region where delta F much less than F bi holds, but also for a whole range of delta F. In order to determine the magnitude of dF, we have used ER to simulate PR, that is, the measurements of ER under a forward bias, which is set to be equal to delta F/2. (C) 1999 American Institute of Physics. [S0021-8979(99)01906-4].
Effects of polarization on electroreflectance spectroscopy of surface-intrinsic n(+)-type doped GaAs
(2002-01-01)
Sung, YG
;
Chiou, SJ
;
Wang, DP
;
Lu, YT
;
Huang, KF
The electroreflectance (ER) spectra of a surface-intrinsic n(+)-type doped (100) GaAs have been measured at various polarization angles of the probe beam. Several Franz-Keldysh oscillations were observed above the band-gap energy, thus enabling heavy- and light-hole transitions to be separated by the application of the fast Fourier transform to the ER spectra. From this, the ratios of the amplitudes of the light- to heavy-hole transitions versus angle of polarization were obtained. At a large incident angle (80 degrees), the strength of the field of the probe beam in the normal direction of the sample (F(z)) was varied from zero to a larger component. It was found that the ratios increased with increasing F(z) which is consistent with the theory that the light-hole transition becomes more enhanced with z-polarized light. (C) 2002 American Institute of Physics.