Browsing by Author "HSU, TM"

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FRANZ-KELDYSH OSCILLATIONS OF DELTA-DOPED GAAS
(1992-08-01)
HSU, TM
;
TIEN, YC
;
LU, NH
;
TSAI, SP
;
LIU, DG
Si-delta-doped GaAs (N2D almost-equal-to 10(11) cm-2) samples grown by molecular-beam epitaxy are investigated by using photoreflectance spectroscopy. The oscillations observed above the GaAs fundamental band gap are attributed to the Franz-Keldysh effect in the region between the delta-doped layer and the crystal surface. This ascription is confirmed by detailed studies through varying the cap thickness (250-2500 angstrom), temperature (10-450 K), and laser pump power (0.05-7 mW/cm2). The surface potential deduced from the Franz-Keldysh oscillations is found to be temperature and laser pump power dependent, which is explained by taking the surface photovoltaic effect into account. The surface Fermi level has been measured by this method and is found to have the value 0.73+/-0.02 V.
PHOTOREFLECTION STUDY ON THE SURFACE ELECTRIC-FIELD OF DELTA-DOPED GAAS GROWN BY MOLECULAR-BEAM EPITAXY
(1992-08-15)
LIU, DG
;
CHANG, KH
;
LEE, CP
;
HSU, TM
;
TIEN, YC
Photoreflectance spectroscopy has been used to study the surface electric-field strength and the surface potential of delta-doped GaAs. Franz-Keldysh oscillations in the reflectance spectra were clearly observed and the oscillation periods were used to calculate the internal electric fields of the delta-doped samples. Based on the measured results and the self-consistent calculation, a surface potential of 0.6 eV is obtained.