ANALYSIS OF AU SI, AL/SI, AND SN/SI SEMICONDUCTOR-DEVICES WITH THIN OXIDE LAYER BY PHOTOCURRENT MEASUREMENTS/

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 wh ite light for illumination. The photocurrent transient effect in Metal /n-Si junctions showed a wide variation upon changing the metal. The p hotocurrent cycles, which consist of fast transient, photocurrent deca y, enhanced photocurrent and persistent photocurrent, are identified f or 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 phi(B) of the junction. The largest degradat ion in phi(B) with the illumination time can be observed for the Sn/Si junction (which has the lowest phi(B)), while the smallest change can be seen in the case of Au/Si junction (which has the highest phi(B)). Upon illumination, the reactivity of the metal with the SiO2/Si inter face is one of the most important factors affecting the oxide layer, a nd phi(B). At room temperature, the lower is the potential barrier hei ght phi(B) of the diode, the faster the photocurrent cycle is produced . On the other hand, at low temperature the larger is the recombinatio n current of the illuminated junction, the faster the photocurrent cyc le is produced. (C) 1997 Elsevier Science S.A.