INFLUENCE OF CARBON AND OXYGEN ON PHOSPHORUS AND ALUMINUM CO-GETTERING IN SILICON SOLAR-CELLS

The impact of carbon and oxygen on the performance of high efficiency photovoltaic devices is still poorly understood. As oxygen is one of t he dominant impurities present in silicon, various applications requir e different levels of oxygen to improve the device performance. In thi s work, we have studied the effects of the oxygen concentration in sil icon on the co-diffusion of phosphorus and aluminium by rapid and conv entional processes. We will compare the effectiveness of the co-diffus ion of P-Al in a variety of silicon materials, as a function of temper ature and duration of the thermal process in a classical and a rapid t hermal furnace and examine the influence of carbon and oxygen on the g ettering efficiency. In particular, we will show that the large enhanc ement of the minority carrier diffusion length (L(D)) due to this proc ess can be related to the presence of oxygen and carbon, the influence of which during the thermal cycle is of importance.