双异质结AlxGa1-xAs/GaAs发光管中与氧有关能级的测量

用DLTS和单次脉冲瞬态电容技术研究了液相外延生长的双异质结AlxGa1-xAs/GaAs发光管,掺Si的n-Al0.05Ga0.95As有源层中的深能级。着重分析了一个与氧有关的电子陷阱,其发射激活能为EC-ED=0.29eV。我们发现该电子陷阱随正向注入脉冲宽度tp的增加DLTS峰向低温移动,即在确定的温度下发射率随tp的增加而增加。用DLTS首次测得该能级的俘获瞬态谱,发现俘获峰随反向撤空脉冲宽度tR的增加向低温端移动,即在确定的温度下俘获率随tR的增加而增加,并且俘获激活能从△Eσ=0.28eV变化到0.26eV,用位形坐标图讨论了引起变化的原因。

AN ELECTRON TRAP RELATED TO OXYGEN IN AlxGa1-xAs/GaAs DOUBLE-HETEROSTRUCTURE LIGHTE-EMITTING

Deep levels in the n-Al0.05Ga0.95As active layer of AlxGa1-xAs/GaAs double-heterostructure light-emitting diode have been studied by using DLTS and single shot transient capacitance methods. Two electron traps and one hole trap were detected for all six oxygen-contaminated samples. DLTS peaks were studied at 145K, 171K and 125K respectively. However, no electron trap can be detected for three samples that have not been contaminated with oxygen. Therefore, we consider that the electron traps are probably related to impurity oxygen. Meanwhile, the electron trap whose DLTS peak is located at 145K was characterized in detail. Firstly, the electron emission activation energy △Eσ of 0.29eV of this trap was determined from an Arrhenius diagr.am. The DLTS peak shifts to lower temperatures while bias pulse duration increases. This shift may be caused by the change of electron capture cross section because the change of electron emission activation energy was not observed. Secondly, the electron capture activation energy △Eσ of 0.26eV was determined by measuring the dependence of amplitude of DLTS peaks on bias pulse duration. The electron capture cross section corresponding to infinite temperature o. was determined to be 1.9×10-12cm2. Single shot transient capacitance technique of directly measuring the capture transient spectroscopy was also used for the first time and the electron capture activation energy △Eσ obtainded is 0.26eV to 0.28eV in accord with the result of the method mentioned before. △Eσ varing from 0.26eV to 0.28eV is due to the change of evaculating pulse duration Such phenomenon can be interpreted as a result of composition fluctuation or mutiple origins of this electron trap. Finally, it was found that the junction capacitance of the diode shows manifest temperature depeneence. This is caused by the temperature dependence of carrier concentrations in Gedoped p-AlxGa1-xAs and Te-doped n-AlxGa1-xAs confinement layers.