放電電流過渡分光法を用いた犠牲酸化処理された高純度半絶縁性4H－SiC の欠陥評価

摘要

当研究室で提案している放電電流過渡分光法（DCTS：Discharge Current Transient Spectroscopy）を用いて高純度半絶縁性4H-SiC の欠陥評価を行ってきた．しかし，半導体内部以外（特に，表面）を定常的に流れる電流が解析に影響していると考えられるため，表面を犠牲酸化処理し，表面電流の低減を試みた．その結果，逆方向電圧100V での漏れ電流は約40％低減できた．このダイオードを用いて，313Kから428Kまでを5K間隔で過渡逆方向電流を測定し，DCTS 法で解析した結果，6種類の欠陥が検出でき，それぞれの活性化エネルギーと捕獲断面積を求めることができた．%To determine the energy levels of intrinsic defects in high-purity semi-insulating 4H-SiC, we apply DCTS (Discharge Current Transient Spectroscopy) that is a graphical peak analysis method based on the transient reverse current of a Schottky barrier diode. However, these transient currents consisted of currents not only in the bulk, but also on the surface of the diode. Therefore, the diode was fabricated with the treatment of sacrificial oxidation. As a result, sacrificial oxidation could dramatically reduce the surface currents of diodes in high-purity semi-insulating 4H-SiC. Using this diode, transient reverse currents measured from 313 K to 428 K were analyzed by DCTS, and six types of intrinsic defects are detected in sacrificial-oxidized high-purity semi-insulating 4H-SiC. From the temperature dependence of the emission rate of each intrinsic defect, its activation energy and capture cross section are determined.