Power loss by two dimensional holes in coherently strained Ge(0.2)Si(0.8)/Si heterostructures evidence for weak screening.

We have used the hot carrier Shubnikov-de Haas effect to measure the power loss by hot two-dimensional holes in coherently strained Ge(0.2)Si(0.8)/Si heterostructures. The dependence of carrier temperature on electric field was determined for field strengths between 1.8 mV/cm and 2.5 V/cm and carrier temperatures between 1.75K and 4.5K. The present modulation doped structures consisted of a single wide (L(w)=500angstroms) quantum well having typical mobilities mu(n) ~ 3,300 cm(2)/V.s and sheet charge densities n(2D) ~ 5 x 10(11) cm(-2). The measured power loss versus carrier temperature data are best described by the two dimensional formulism of Price [J. Appl. Phy. 53, 6864 (1982)] assuming weak (negligible) screening. Excellent agreement with experiment is obtained only if scattering of the acoustic mode phonons by both the deformation potential and the plezoelectric coupling mechanisms are considered.