Analysis of Au-, Al-, and Sn/Si semiconductor devices with thin oxide layer by photocurrent measurements

Abstract

We present herein a photocurrent study on the forward biased Au-, Al-, and Sn/ n-Si junctions with the native oxide layer using an intense white light for illumination. The photocurrent transient effect in Metal/ n-Si junctions showed a wide variation upon changing the metal. The photocurrent cycles, which consist of fast transient, photocurrent decay, enhanced photocurrent and persistent photocurrent, are identified for each M/Si junction at temperatures 120 K and 300 K. The cycle seems to be strongly dependent on the oxide thickness, and subsequently the potential barrier height φ B of the junction. The largest degradation in φ B with the illumination time can be observed for the Sn/Si junction (which has the lowest φ B), while the smallest change can be seen in the case of Au/Si junction (which has the highest φ B). Upon illumination, the reactivity of the metal with the SiO 2/Si interface is one of the most important factors affecting the oxide layer, and φ B. At room temperature, the lower is the potential barrier height φ B of the diode, the faster the photocurrent cycle is produced. On the other hand, at low temperature the larger is the recombination current of the illuminated junction, the faster the photocurrent cycle is produced.