Title :
Capacitance studies of a-SiGe:H p-i-n solar cells
Author :
Hegedus, Steven S.
Author_Institution :
Inst. of Energy Conversion, Delaware Univ., Newark, DE, USA
Abstract :
An equivalent circuit model was used to fit the measured conductance (G) and capacitance (C) of a-Si:H and a-SiGe:H p-i-n and Schottky diodes using EA, g 0, and v as the main fitting parameters. The midgap density of states (MGDOS) was determined using steady-state admittance measurements on typical a-Si:H and a-SiGe:H p-i-n solar cells, C and G were measured as a function of temperature and frequency. The junction and bulk were each modeled by a capacitor and resistor, and the lumped equivalent circuit was analyzed. Good agreement is found between measured and predicted values of both C and G with the MGDOS and EF, as fitting parameters. Analysis of Schottky and p-i-n cells indicates that the influence of space charge in doped layers is negligible and that the p-i-n cell can be represented by a single space charge region in series with the bulk. The MGDOS values derived from the circuit model for a-Si:H and a-SiGe:H are in good agreement with those from other measurements
Keywords :
Ge-Si alloys; amorphous semiconductors; capacitance; electronic density of states; elemental semiconductors; equivalent circuits; hydrogen; semiconductor device models; silicon; solar cells; Scholtby cells; amorphous SiGe:H; capacitance; conductance; equivalent circuit model; midgap density of states; p-i-n solar cells; steady-state admittance measurements; Admittance measurement; Capacitance measurement; Density measurement; Equivalent circuits; Frequency measurement; PIN photodiodes; Photovoltaic cells; Schottky diodes; Space charge; Steady-state;
Conference_Titel :
Photovoltaic Specialists Conference, 1990., Conference Record of the Twenty First IEEE
Conference_Location :
Kissimmee, FL
DOI :
10.1109/PVSC.1990.111867
