Electrochemical capacitance-voltage profiling of nonuniformly doped GaAs heterostructures with SQWs and MQWs for LED applications


Abstract: Light-emitting heterostructures with single and multiple GaAs/InGaAs quantum wells have been investigated by means of electrochemical capacitance-voltage (ECV) profiling. Capacitance-voltage characteristics were measured; concentration profiles of free charge carriers over the heterostructure depth as well as the intensity of quantum well filling by charge carriers were obtained. In heterostructures with a single quantum well (QW), we considered limitations of capacitance techniques for undoped QW profiling, which are situated near the metallurgic border of the p-n junction. We made a detailed consideration of phenomena related to Debye smearing and we developed and analyzed the dependence of the space charge region width on the doping. Special attention was paid to investigation of "the blind" area. This was inspired by the practical problem from capacitance spectroscopy of semiconductors, when the researcher poses the task of obtaining a free charge carrier depth distribution profile as deep as possible in the space charge region, i.e. where the intensity of the electric field is maximum. Generally, the active QW of a LED heterostructure is placed deep in the space charge region, so reaching these regions is extremely important for practical problems. We present an evolution of capacitance-voltage characteristics during ECV profiling of nonuniformly doped p-n-heterostructures. For a heterostructure with multiple quantum wells, we registered a response from 6 QWs.

Keywords: Electrochemical capacitance-voltage profiling, heterostructure, light-emitting diodes, quantum well, quantum dot, capacitance-voltage profiling, nonuniform doping

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