DOI: https://doi.org/10.30970/jps.02.376
PIEZOPHOTOCONDUCTIVE SPECTRA IN MONOPOLAR SEMICONDUCTORS
|
Journal of Physical Studies 2(3), 376–383 (1998)
DOI: https://doi.org/10.30970/jps.02.376 PIEZOPHOTOCONDUCTIVE SPECTRA IN MONOPOLAR SEMICONDUCTORS |
|
J. M. Stakhira1, R. J. Stakhira2
1The Ivan Franko State University of Lviv, Chair of Semiconductor Physics,
50 Drahomanov Str., Lviv, UA–290005, Ukraine
2State University Lviv Polytechnic",
12 S. Bandera Str., Lviv, UA–290601, Ukraine
Piezophotoconductivity of monopolar semiconductors has been analyzed. This phenomenon is brought about by a common action of light from the spectrum range that corresponds to interband absorption and by the low frequency mechanical pressure. The case of \ the concentration mechanism of bringing about this effect is examined. The main equation that describes the concentration dynamics of the nonequillibrium current carriers $n(t)$ in conditions of acousto–optical excitation is as follows
$$ {d^2n(t)\over dt^2}+Ω^2n(t) = {d\over dt}(G-R), (1) $$
where $W$ is the frequency of mechanical pressure, $G$ and $R$ are generation and recombination rates of nonequillibrium current carriers.
The right side of equation (1) is extended by the calculated generation rate for the case of nonstationary electron states
$$ G(t) = G_0+G_1\cosΩ t+G_2\sinΩ t, (2) $$
where $G_1$ and $G_2$ are values expressed through Bessel's functions of zero and first order. The main equation of Shockley–Read's theory is used for the recombination rate.
The solutions of equation (1) for these cases are received for the regime that is determined by the average method for high and small excitation levels. The main conclusions of the calculations are the following:
1) The concentration of nonequillibrium current carriers can considerably increase at the decreasing of recombination rate. The case of nonlinear resonance can be realized at low rate levels.
2) The current of piezophotoconductivity can be shifted on the phase as regards the mechanical pressure phase for the angle value which is determined by the ratio between the orthogonal component of generation rates and the degree of recombination rate nonlinearity.
3) The spectrum of sensitive piezophotoconductivity has an oscillating character and the spectrum of synphase component is mainly described by Bessel's function of a zero order and the spectrum of the orthogonal component is described by a derivative from this function.
4) The set of zero points in spectra of orthogonal constituents depends on the energy of light quantum and on the sensitivity of energetic states to mechanical pressure.