研究目的
To investigate special aspects of FCC depth distribution in modern GaAs LED heterostructures and to analyze the ECV technique resolution in the case of nonuniform doping profile measurements.
研究成果
The ECV technique was successfully used to investigate GaAs/InGaAs heterostructures with SQWs and MQWs. Limitations of capacitance profiling techniques for undoped QWs were considered, and the 'blind' area was investigated in detail. For MQWs, a response from 6 QWs was registered, confirming the hypothesis about the 'blind' area.
研究不足
The presence of a 'blind' area in capacitance measurements due to the location of the QW in the maximum of the p–n–junction electric field. Debye smearing effects and change of conductivity type add to the limitations due to the sharp SCR width increase in the vicinity of the QW.
1：Experimental Design and Method Selection:
The study employed electrochemical capacitance-voltage (ECV) profiling to investigate GaAs/InGaAs quantum wells. The methodology included measuring capacitance-voltage characteristics and obtaining concentration profiles of free charge carriers.
2：Sample Selection and Data Sources:
A set of 5 GaAs heterostructures intended for fabrication of IR light-emitting diodes was examined. Samples differed by doping level and layer width.
3：List of Experimental Equipment and Materials:
ECVPro (Nanometrics) was used for FCC depth distribution measurements. Tiron (0.1 M) was used as an electrolyte. An Agilent E4980A was used for some experiments, and a Solver NEXT atomic-force microscope was used to control etching depth and quality.
4：1 M) was used as an electrolyte. An Agilent E4980A was used for some experiments, and a Solver NEXT atomic-force microscope was used to control etching depth and quality.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The measurements were carried out at room temperature. Etching current was at the level of 0.5 mA/cm2. Etching step was 1 nm. Bias V in ECV measurements was chosen at the linear region of C-V characteristics at Mott–Schottky coordinates.
5：5 mA/cmEtching step was 1 nm. Bias V in ECV measurements was chosen at the linear region of C-V characteristics at Mott–Schottky coordinates.
Data Analysis Methods:
5. Data Analysis Methods: The FCC concentration was calculated as the derivative of the measured dependence of capacitance vs. bias. The location of the space charge region edge was defined using specific formulas.
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