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
Ç. Ş. Güçlü, Esra Erbilen Tanrıkulu, Murat Ulusoy, Y. Azizian Kalandargh, Ş. Altındal
Abstract
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 + j ωC ) 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 ( N D ), diffusion potential ( V D ), Fermi-energy ( E F ), barrier height Φ B ( C - V ), depletion-layer thickness ( W D ), and maximum electric field ( E m ) were calculated from these measurements for each frequency. These values were found as 1.69 × 10 16 cm −3 , 0.444 eV, 0.193 eV, 0.606 eV, 1.31 × 10 −5 cm, 7.66 × 10 4 V/cm for 10 kHz, and 1.42 × 10 16 cm −3 , 0.461 eV, 0.198 eV, 0.628 eV, 1.46 × 10 −5 cm, 7.80 × 10 4 V/cm for 3 MHz, respectively. While N D decreases with increasing frequency, the other parameters increase. The density of surface states ( N ss ) and their lifetimes ( τ ) were also obtained from conductance techniques. While the N ss were changed between 2.78 × 10 12 at 0.40 V and 2.61 × 10 12 eV -1 cm −2 at 1.3 V, and the N ss -V curve shows two distinctive peaks which correspond to 0.5 V (2.87 × 10 12 eV −1 cm −2 ) and 1.2 V (2.68 × 10 12 eV −1 cm −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 N ss were attributed to the used (ZnCdS-GO:PVP) interlayer.