Admittance spectroscopy of GaAs/InGaP MQW structures

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) using tertiarybutylarsine and tertiarybutylphosphine as alternative precursors for the V group elements. Through the analysis of the temperature dependence of the resonance frequency _ at which the isothermal curves of the conductance over frequency G(ω)/ω 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 (Ehh 1 = 10 meV). Experimental values of _EV previously reported in the literature spread over the wide range of 300–400 meV.