Istituto dei materiali per l'elettronica ed il magnetismo     
Ghezzi C., Magnanini R., Parisini A., Tarricone L., Gombia E., Longo M. Determination of the valence band offset of MOVPE-grown In0.48Ga0.52P/GaAs multiple quantum wells by admittance spectroscopy. In: Physical Review B, vol. 77 article n. 125317. The American Physical Society, 2008.
The valence band discontinuity of the lattice matched InGaP/GaAs heterostructure was determined through a careful analysis of the temperature and frequency dependence of the admittance of p+/MQW/n+ structures where a nominally undoped InGaP/GaAs MQW region is interposed between p+ and n+ GaAs. The heterostructures were grown through Metal Organic Vapour Phase Epitaxy (MOVPE) by using tertiarybutyl arsine (TBAs) and tertiarybutyl phosphine (TBP) as alternative precursors for the V group elements. The growth conditions were optimized for obtaining sharp interfaces and negligible ordering effects in the cation sublattice. Accounting for the temperature dependence of the Fermi energy and the calculated confining energy (10 meV) of heavy holes in the wells a valence band offset ?EV=(356+-5) meV was derived from the temperature variation of the resonance frequency at which the isothermal conductance over frequency G(?)/? curves show a maximum. The experimental uncertainty of this result is significantly low if compared with the wide range (240-400 meV) of the previously reported ?Ev values. By considering the band gap difference between InGaP and GaAs, a conduction band offset ?Ec=119 meV was estimated. The accuracy of the experimental procedure and the reliability of the main assumptions of the admittance spectroscopy measurements were accurately checked. The obtained results are discussed at the light of the large spreading of the literature data by taking into account the influence of the growth conditions on the physical properties of the InGaP/GaAs quantum wells.
URL: http://link.aps.org/doi/10.1103/PhysRevB.77.125317
DOI: 10.1103/PhysRevB.77.125317
Subject Band Offsets
Admittance Spectroscopy
73.40.Kp, 73.21.Fg, 73.61.Ey

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