O. Rousiere et al., ELECTRICAL CHARACTERIZATION OF THE P-HG1-XZNXTE INTERFACE AFTER ANODIC SULFIDIZATION TREATMENTS, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 16(4), 1998, pp. 2300-2308
Citations number
23
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
We have investigated the p-Hg1-xZnxTe interface, with x in the range o
f 0.19-0.23, after electrochemical treatments with Na2S in ethylene gl
ycol using admittance spectroscopy of metal-insulator-semiconductor st
ructures made on these passivated surfaces. Native sulfide layers are
characterized from angle-resolved x-ray photoelectron spectroscopy mea
surements and are constituted mainly by ZnS. The surface roughness is
ascertained by atomic force microscopy. Free carriers densities and th
e degree of compensation for the semiconductor are deduced from capaci
tance measurements: the method is based on a numerical analysis of the
normalized capacitance measured at high frequency as a function of th
e bias voltage. The positive fixed charge density in the native sulfid
e layer is found to be in the range of 10(10)-10(11) cm(-2) as deduced
by the shift in the C-V characteristics. C-V plots show a very small
hysteresis effect at 77 K, resulting in a low density of slow surface
states (similar to 1 x 10(10) cm(-2)). The energy distribution of fast
interface states is calculated in two ways from capacitance and condu
ctance measurements. The conductance method shows a higher sensitivity
. A broad U-shape distribution is obtained for the different samples s
tudied, with a reproducible minimum density of about a few 10(10) eV(-
1) cm(-2); The best passivation conditions are obtained with a constan
t current density of about 100 mu A cm(-2) and a sulfidization duratio
n of similar to 15 min. The time constant of the interface traps is de
duced from the energy loss peak and leads to an estimation of their ca
pture cross section. All these results show that a very high interface
quality can be obtained on p-Hg1-xZnxTe in a reproducible way by anod
ic sulfidization. (C) 1998 American Vacuum Society. [S0734-2101 (98)03
704-X].