Infrared absorption and photocurrent measurements have been applied to study the photoresponse below the band gap of indium gallium arsenide (In 0.53Ga0.47As) grown lattice matched to Fe-doped semi-insulating indium phosphide (InP) substrates by various epitaxial growth techniques, including molecular beam epitaxy, liquid phase epitaxy, and metalorganic chemical vapor deposition. It is found that Fe at the InGaAs/InP interface is responsible for exciton-like and polarization sensitive absorption peaks. Both electron and hole emission into the conduction and valence bands, respectively, were observed, and a deep Fe level was identified 0.37 eV below the conduction band edge of bulk Fe:InGaAs. Lowering of the local crystal symmetry due to the interface electric field is proposed to be the mechanism that describes the dipole-allowed interband absorption of 3d transition metal impurities in narrow band gap III-V compounds like the Fe2+:InGaAs used in this study. The ambiguity in distinguishing InGaAs quantum well intersubband absorption signals from the Fe interband absorption signals is also addressed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)