ZnSe GaAs band-alignment determination by deep level transient spectroscopy and photocurrent measurements

Using deep level transient spectroscopy and photocurrent measurements we ha ve investigated Schottky contacts formed on p-isotype Zn(SSe)/GaAs heterost ructures grown by molecular beam epitaxy on p-GaAs( 100) substrates. A deep level located at 0.6 eV above the ZnSe valence band is observed in agreeme nt with literature data for p-type ZnSe, and is used as a reference level f or the understanding of photocurrent transitions in the 0.8-3.0 eV energy r ange. The threshold energies obtained on a series of Zn(SSe)/GaAs samples a re explained in terms of absorption processes from the ZnSe and GaAs valenc e bands, and from the nitrogen acceptor level and a deep level of the ZnSe layers located at 0.1 and 0.6 eV above the valence band maximum, respective ly. These absorption processes towards the ZnSe and GaAs conduction bands h ave been finally used to give the values of the conduction and valence band offsets at p-ZnSe/p-GaAs interface. Our experimental data gives Delta E-c = 0.25+/-0.03 eV and Delta E-u = 1.00 +/- 0.05 eV in agreement with literat ure data for Zn-rich interfaces. (C) 1999 American Institute of Physics. [S 0021-8979(99)01009-9].