Enhanced sensing capabilities of UV–visible p-n and p-i-n photodiodes using unique layer and contact configurations

Abstract

This paper focuses on the ultraviolet–visible (UV–vis) light response of the p-n and p-i-n vertical self-powered photodiodes (PDs) based on p-PMItz/n-Si, p-PMItz/n-4HSiC and p-PMItz/i-SiO₂/n-Si Heterojunctions. The PDs, referred to as Device A-B-C-D-E and F according to the modified structures, were produced to increase the sensing capacity using distinct anode contacts. The basic fundamental parameters were recorded using the I-V data of PDs with thermionic emission theory (TE) and Ohm’s law. The results showed that, in line with the literature, the potential barrier height (Ф_Bo) decreased, and the ideality factor (n) increased with increasing illumination intensity. Additionally, the voltage-dependent series resistances (R_s) of PDs in the dark and under different UV–vis light intensities were determined using Ohm’s laws. It was recorded that R_s decreased as light intensity increased. On the other hand, the photosensitivity properties of PDs in UV–vis intensities depending on the voltage were investigated. The photosensitivity of the fabricated Device B reached a maximum of 4.05x10⁴ at short circuit voltage (V_sc = 0 V). In contrast, when self-powered, the short-circuit voltage (V_oc) showed better photosensitivity (with a minimum of 0.058). Additionally, the specific detectivity (D*) and the responsivity (R) of the PDs were calculated. According to the literature, the R and D* decreased with increasing power density at zero-bias voltage. Also, the R of Device B is higher, and D* is lower than other devices. The linear dynamic range (LDR) of Device A reaches ∼ 92 dB with maximum (V_bias = 0 V) while the dark current is 0.038 nA with minimum (in self-powered mode). Device B is considered suitable for the PDs (in self-powered mode) among other devices.