Fabrication and characterization of amorphous ITO/p-Si heterojunction solar cell

Amorphous indium-tin-oxide (a-ITO) film was deposited by radio-frequency (RF) magnetron sputtering at 180A degrees C substrate temperature on the texturized p-Si wafer to fabricate a-ITO/p-Si heterojunction solar cell. The microstructural, optical and electrical properties of the a -ITO film were characterized by XRD, SEM, XPS, UV-VIS spectrophotometer, four-point probe and Hall effect measurement, respectively. The electrical properties of heterojunction were investigated by I-V measurement, which reveals that the heterojunction shows strong rectifying behavior under a dark condition. The ideality factor and the saturation current density of this diode are 2.26 and 1.58x10(-4) A cm(-2), respectively. And the value of I (F)/I (R) (I (F) and I (R) stand for forward and reverse currents, respectively) at 1 V is found to be as high as 21.5. For the a-ITO/p-Si heterojunction solar cell, the a-ITO thin film acts not only as an emitter layer, but also as an anti-reflected coating film. The conversion efficiency of the fabricated a-ITO/p-Si heterojunction cell is approximately 1.1%, under 100 mW cm(-2) illumination (AM1.5 condition). And the open-circuit voltage (V (oc)), short-circuit current density (J (SC)), filll factor (FF) are 280 mV, 9.83 mA cm(-2) and 39.9%, respectively. Because the ITO film deposited at low temperature is amorphous, it can effectively reduce the interface states between ITO and p-Si. The barrier height and internal electric field, which is near the surface of p-Si, can effectively be enhanced. Thus we can see the great photovoltaic effect.