PHOTOCONDUCTIVE ANALYSIS OF DEFECT DENSITY OF HYDROGENATED AMORPHOUS-SILICON DURING ROOM-TEMPERATURE PLASMA POSTHYDROGENATION, LIGHT SOAKING, AND THERMAL ANNEALING
Jp. Condo et al., PHOTOCONDUCTIVE ANALYSIS OF DEFECT DENSITY OF HYDROGENATED AMORPHOUS-SILICON DURING ROOM-TEMPERATURE PLASMA POSTHYDROGENATION, LIGHT SOAKING, AND THERMAL ANNEALING, Physical review. B, Condensed matter, 53(4), 1996, pp. 1886-1890
The photoconductivity (sigma(ph)) of thin (less than or equal to 1000
Angstrom) hydrogenated amorphous silicon films (a-Si:H) was measured a
s a function of time to monitor the defect density during remote induc
tively coupled plasma (ICP) posthydrogenation at room temperature, lig
ht soaking (performed both before and after posthydrogenation), and is
othermal annealing (performed after posthydrogenation and light soakin
g), and fitted to a stretched exponential curve. A decrease of sigma(p
h)(t) during posthydrogenation at room temperature was observed and re
lated to the breaking of Si-Si weak bonds by individual hydrogen atoms
. Upon thermal annealing, the initial equilibrium defect density was r
ecovered. The stretched exponential parameters beta and tau of sigma(p
h)(t) were the same for the isothermal anneals performed after light s
oaking and after plasma posthydrogenation, indicating that the defects
introduced in both cases were of similar nature. The stretched expone
ntial parameters beta and tau of sigma(ph)(t) were also the same for t
he light soaking before and after plasma posthydrogenation, suggesting
that posthydrogenation did not alter the susceptibility of the materi
al to light-induced degradation. a-Si:H samples deposited by remote IC
P, hot-wire, and rf glow discharge were studied. The increase of hydro
gen concentration in the samples during posthydrogenation was measured
by infrared spectroscopy.