Silicon Heterojunction Solar Cells Using AlO<i>_x</i> and Plasma-Immersion Ion Implantation

Aluminum oxide (AlO<i>_x</i>) and plasma immersion ion implantation (PIII) were studied in relation to passivated silicon heterojunction solar cells. When aluminum oxide (AlO<i>_x</i>) was deposited on the surface of a wafer; the electric field near the surface of wafer was enhanced; and the mobility of the carrier was improved; thus reducing carrier traps associated with dangling bonds. Using PIII enabled implanting nitrogen into the device to reduce dangling bonds and achieve the desired passivation effect. Depositing AlO<i>_x</i> on the surface of a solar cell increased the short-circuit current density (<i>J</i>_sc); open-circuit voltage (<i>V</i>_oc); and conversion efficiency from 27.84 mA/cm²; 0.52 V; and 8.97% to 29.34 mA/cm²; 0.54 V; and 9.68%; respectively. After controlling the depth and concentration of nitrogen by modulating the PIII energy; the ideal PIII condition was determined to be 2 keV and 10 min. As a result; a 15.42% conversion efficiency was thus achieved; and the <i>J</i>_sc; <i>V</i>_oc; and fill factor were 37.78 mA/cm²; 0.55 V; and 0.742; respectively.