Research On The Electroluminescence Properties Of Ge/In_xGa(1-x)As Heterojunction

Because of its higher electron mobility and hole mobility, its compatibility with silicontechnology, and its136meV gap between bottom of direct conduction band and indirectconduction band, the germanium is of great importance in both high speed integratedcircuit and light-emitting devices. The tensile-strained germanium got extensiveattention as gain medium for luminescent device since tensile-strain can reduce the gapbetween bottom of direct conduction band and indirect conduction band.The germanium layers were grown on InxGa1-xAs buffer layer as intrinsic layer of lightemitting diode in this thesis. Biaxial tensile-strain in germanium is introduced by latticemismatch between germanium and InxGa1-xAs to study the ElectroluminescenceProperties of Ge/InxGa1-xAs Heterojunction. All simulation have done by Atlas ofSilvaco. InxGa1-xAs has specific lattice constant according to different indiumconcentration, and lead to different degree of lattice mismatch between germanium andInxGa1-xAs. The magnitude of strain in germanium was controlled by changing indiumconcentration in InxGa1-xAs. Firstly some basic settings, carrier distribution, energyband and basic electroluminescence properties were obtained when x was0.25,corresponding tensile-strain was1.7%in germanium. And the corresponding radiativerecombination rate, and electroluminescence intensity, when x is respectively equal to0.15、0.2、0.25、0.3、0.4were obtained through simulation.The magnitude of strain in germanium increases with the increment of indiumconcentration in InxGa1-xAs, beyond that, the radiative recombination rate of carrier andelectroluminescence intensity also have the same trend. Change of germanium Energyband structure caused by tensile-strain was consistent with theoretical analysis, whichwas proved by simulation indirectly. So tensile-strained germanium can applied tolight-emitting devices, and this paper laid a foundation for further research ofapplication of tensile-strained germanium in light-emitting devices.