Admittance spectroscopy of GaAs/InGaP MQWstructures

An accurate determination of the valence band discontinuity of the lattice matched GaAs/InGaP heterostructure is performed by admittance spectroscopy measurements in p+/MQW/n+ structures grown by metal-organic vapour phase epitaxy (MOVPE). Through the analysis of the temperature dependence of the resonant frequency at which the isothermal curves of the conductance over frequency have the maximum, the energy separation of 336+-5 meV between the lowest heavy hole quantum level in the GaAs wells and the InGaP valence band top is obtained. A valence band discontinuity of Ev=346+-5 meV is then derived by accounting for the calculated confinement energy of heavy holes.