The piezoelectric (PE) and pyroelectric properties of strained 〈111〉-oriented InGaAs layers have recently attracted interest because they provide additional device design parameters. However, there still exists a substantial uncertainty as to the value of the PE constant e 14 as well as the value and sign of the pyroelectric coefficient. We applied both photoreflectance and contactless electroreflectance (CER) spectroscopy to assess the PE and pyroelectric properties of a strained InGaAs/GaAs quantum well (QW) structure grown on a (111)A GaAs substrate by metal organic vapor phase epitaxy. Photoreflectance and CER spectroscopy provide information on high-order QW transitions as well as the Franz-Keldysh oscillations that develop in the presence of electric fields in the GaAs barriers and lead to an accurate determination of the temperature dependence of the PE field and constant e 14 . High-resolution X-ray diffractometry and transmission electron microscopy were employed to independently determine the structural parameters and verify the high crystal quality of the QW structure. We observed a linear temperature dependence of the PE field and e 14 in the range 25 -300 K. To our knowledge, this is the first observation of the pyroelectric effect in strained InGaAs layers grown on (111)A GaAs substrates.

We solve a pair of Boltzmann transport equations based on an interacting two-isotropic-band model in a general way first to get transport parameters corresponding to the relaxation time. We present a simple method to calculate effective relaxation times, separately for each band, which compensate for the inherent deficiencies in using the relaxation time concept for polar optical-phonon scattering. Formulas for calculating momentum relaxation times in the two-band model are presented for all the major scattering mechanisms of p-type GaAs for simple, practical mobility calculations. In the newly proposed theoretical framework, first-principles calculations for the Hall mobility and Hall factor of p-type GaAs at room temperature are carried out with no adjustable parameters in order to obtain direct comparisons between the theory and recently available experimental results. In the calculations, the light-hole-band nonparabolicity is taken into account on the average by the use of energy-dependent effective mass obtained from the k-p method and valence-band anisotropy is taken partly into account by the use the Wiley's overlap function.. The calculated Hall mobilities show a good agreement with our experimental data for carbon-doped p-GaAs samples in the range of degenerate hole densities. The calculated Hall factors show r H ϭ1.25-1.75 over hole densities of 2ϫ10 17 -1ϫ10 20 cm Ϫ3 .

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We present the heterointerfacial properties of GaAs/AlGaAs multiquantum-well structures grown by atmospheric-pressure metalorganic vapor phase epitaxy on (111)A GaAs substrates at a relatively low growth temperature of 600 °C. For a 25-period GaAs/Al0.27Ga0.73As multiquantum-well structure with a well width of 44 Å, a photoluminescence linewidth of 10.5 meV was observed, which is smaller than previously reported for a similar GaAs/AlGaAs multiquantum-well structure grown by molecular beam epitaxy on (111)A GaAs. As this linewidth corresponds to a combined well-width fluctuation and interfacial roughness throughout the 25 periods of at most ±1 monolayer, it is concluded that epitaxial growth on the (111)A surface can result in high-quality heterointerfaces, particularly at low growth temperatures.

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