Comparative Electrical and Photoresponse Investigation of the Au/PVA/n <i>-</i> Si ( <i>MPS1</i> ) and Au/(CdTe:PVA)/n-Si ( <i>MPS2</i> ) Photodiodes, Both in the Dark and under Illumination

In this current article, Au/n-Si (metal/semiconductor) <i>MS</i> devices with high-purity poly-(vinyl alcohol) (PVA) (99+% hydrolyzed) (<i>MPS1</i>) and Au/(CdTe:PVA)/n-Si (metal/polymer/semiconductor) (<i>MPS2</i>) are grown on the same n-type Si wafer by using the spin-coating technique and determine their effects on light sensitivity and basic electronic parameters like saturation current (<i>I</i> ₀), which is derived from the straight-line intercept of ln-(<i>I</i>) at <i>V</i> = 0, zero-bias barrier height (ϕ <i>_b</i> ₀) at <i>V</i> = 0, ideality/quality factor (<i>n</i>), and both the shunt/series resistances (<i>R</i> _<i>s</i> , <i>R</i> _sh). For this purpose, the current-voltage (<i>I</i>-<i>V</i>) measurement is carried out over a wide voltage range (±4.5 V), both in the dark and under 100 mW/cm² conditions. Experimental results showed that the calculated electrical parameters were highly dependent on light, the organic interlayere, and voltage. The profile of interface states <i>(N</i> _<i>ss</i> ) dependent on energy and voltage-dependent resistance <i>(R</i> _<i>i</i> ), which significantly limit the performance of the photodiode, wwas obtained from the Card-Rhoderick model and Ohm's law for both before and after illumination, respectively. In addition, voltage-dependent curves of the photosensitivity, photoresponsivity (<i>R</i>), and specific detectivity (<i>D*</i>) were obtained for the 100 mW·cm^-2 intensity. When the results obtained for <i>MPS1</i> and <i>MPS2</i> photodiodes were compared with each other and with the existing literature, it was observed that the <i>MPS2</i> exhibited significantly better performance. Therefore, it was shown that <i>MPS2</i> with the (CdTe:PVA) interlayer could be a good candidate for electrical, optical, and energy conversion applications.