Observation of the pyroelectric effect in strained piezoelectric InGaAs/GaAs quantum-wells grown on (111) GaAs substrates

We investigated the temperature dependence of the piezoelectric constant e₁₄, i.e. the pyroelectric effect, of various strained InGaAs/GaAs single- and multi-quantum wells embedded in p-i-n structures grown on (111)B GaAs substrates and diodes made from these structures. Both photoreflectance spectroscopy and differential photocurrent spectroscopy were applied to obtain e₁₄ over the temperature range 11-300 K. The values of e₁₄ for In_xGa_1−xAs quantum well layers with x=0.12-0.21 were observed to increase with temperature, which is contrary to the expected dependence, and the strain-induced components of the pyroelectric coefficients were quantitatively determined. The dependence of the pyroelectric coefficient on In fraction is discussed.