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) using tertiarybutylarsine and tertiarybutylphosphine as alternative precursors for the V group elements. Through the analysis of the temperature dependence of the resonance frequency (omega) over bar at which the isothermal curves of the conductance over frequency G(omega)/omega 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 Delta E-V = 346 +/- 5 meV is then derived by accounting for the calculated confinement energy of heavy holes (E-1(hh) = 10 meV). Experimental values of Delta E-V previously reported in the literature spread over the wide range of 300-400 meV. (C) 2007 Elsevier B.V. All rights reserved.