Characterization of piezoelectric and pyroelectric properties of MOVPE‐grown strained (111)A InGaAs/GaAs QW structures by modulation spectroscopy

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.