Frequency-dependent physical parameters, the voltage-dependent profile of surface traps, and their lifetime of Au/(ZnCdS-GO:PVP)/n-Si structures by using the conductance method

Abstract

In this study, frequency-dependent physical parameters, voltage-dependent of surface traps/states, and their lifetime of the Au/(ZnCdS-GO:PVP)/n-Si (MPS) type structures were investigated by using conductance measurements (Y = 1/Z = G + jωC) both in wide range frequency (3 kHz-3 MHz) and voltage (from − 4.00 V to 1.50 V). Firstly, basic physical parameters such as density of doping donor atoms (ND), diffusion potential (VD), Fermi-energy (EF), barrier height ΦB(C-V), depletion-layer thickness (WD), and maximum electric field (Em) were calculated from these measurements for each frequency. These values were found as 1.69 × 1016 cm−3, 0.444 eV, 0.193 eV, 0.606 eV, 1.31 × 10−5 cm, 7.66 × 104 V/cm for 10 kHz, and 1.42 × 1016 cm−3, 0.461 eV, 0.198 eV, 0.628 eV, 1.46 × 10−5 cm, 7.80 × 104 V/cm for 3 MHz, respectively. While ND decreases with increasing frequency, the other parameters increase. The density of surface states (Nss) and their lifetimes (τ) were also obtained from conductance techniques. While the Nss were changed between 2.78 × 1012 at 0.40 V and 2.61 × 1012 eV-1cm−2 at 1.3 V, and the Nss-V curve shows two distinctive peaks which correspond to 0.5 V (2.87 × 1012 eV−1cm−2) and 1.2 V (2.68 × 1012 eV−1cm−2), respectively. The values of τ were changed between 105 µs (at 0.4 V) and 15.3 µs (at 1.3 V) and decreased with increasing voltage as exponentially. These lower values of Nss were attributed to the used (ZnCdS-GO:PVP) interlayer.