INVERSION LAYER SOLAR CELLS USING IONIZING RADIATION-INDUCED SURFACE INVERSION IN INDIUM OXIDE/SILICON DIOXIDE/SILICON STRUCTURES (RADIATION HARD)

A novel application of the effects of ionizing radiation on MOS structures is presented in this dissertation. It will be shown that high efficiency inversion layer solar cells, having an In(,2)O(,3)/SiO(,2)/Si MOS as a basic structure, can be made by using ionizing radiation to produce the required inversion layer. An average total area efficiency of over 15 percent under simulated AM1 illumination, with a highest value of 16.0 percent, has been achieved without antireflection coating.;The key to the success of this method is the fact that exposure of the In(,2)O(,3) MOS structure to X-rays, with positive bias on the gate, creates a large amount of positive oxide charge without generating an appreciable density of interface traps. In contrast, for a similar MOS structure with an aluminum electrode, a very large density of interface traps is generated by the same X-ray treatment.;Extensive experimentation has demonstrated that, in addition to the favorable interfacial stress distribution in the MOS structure induced by the In(,2)O(,3) film, the radiation hardness of the In(,2)O(,3) MOS structure arises mainly from the low concentration of water or hydrogen related sites in the oxide, resulting from the built-in vacuum bake treatment during the In(,2)O(,3) evaporation process. Through this finding, the mechanisms of the generation of radiation-induced interface traps become much clearer. This vacuum bake process may also be utilized to fabricate radiation-hard devices for other applications.;Compared to a conventional p-n junction cell, the inversion layer cell has a much better short wavelength response. Moreover, a stability test of the cell at elevated temperature has shown essentially no degradation after the cell is held at 200(DEGREES)C for several months.