Piezoresistance and Piezo-Hall Effects inn-ZnSe

Abstract

Large piezoresistance and piezo-Hall effects were observed in $n$-ZnSe samples. The experimental result for the shear piezoresistance coefficient, ${\pi }_{\mathrm{shear}}\approx 0$, is consistent with the model that the lowest conduction-band minimum for this material lies at K = (0,0,0). The large piezoresistance and piezo-Hall effects can be qualitatively explained on the basis of the large pressure dependence of the donor ionization energy ${\epsilon }_d$. The data on the longitudinal coefficient ${\pi }_l\left(\rho \right)$ versus $T$ give a value ${\epsilon }_d\approx 0.019$ eV, in excellent agreement with the value ${\epsilon }_d\approx 0.020$ eV estimated from the low-temperature data on the resistivity $\rho$ versus $T$. The result $\left(\frac{d{\epsilon }_d}{\mathrm{dP}}\right)\ge +5.2\mathrm{}\times {10}^{-12\mathrm{}}$ eV/dyn ${\mathrm{cm}}^{-2\mathrm{}}$ was obtained from the pressure data at 195°K, and suggests that there is considerable contribution from some band other than the (0,0,0) conduction band to the donor state functions. The piezoresistance data around 20°K, when simply interpreted on the basis of the pressure dependence of the ionization energy of the single donor level, gave the value $\left(\frac{d{\epsilon }_d}{\mathrm{dP}}\right)\approx +2.6\mathrm{}\times {10}^{-12\mathrm{}}$ eV/dyn ${\mathrm{cm}}^{-2\mathrm{}}$, in disagreement with the estimate obtained from the pressure data at 195°K.