In this study, Al/(ZnO–PVA)/p-Si (MPS type) Schottky diodes (SDs) were fabricated instead of metal–semiconductor (MS) type SDs with traditional insulator interfacial layer. Additionally, basic electrical parameters of these MPS-type SDs (such as doping acceptor atoms (NA), depletion layer width (WD), series resistance (Rs), barrier height (ΦB), and surface states/traps (Nss/Nit)) were found as a function of gamma-irradiation by using the capacitance/conductance–voltage (C/G–V) measurements. These measurements under 0–60 kGy radiation doses show that radiation-induced Nss are more effective in the depletion layer. On the other hand, voltage-dependent profiles of Rs and Nss were also obtained using Nicollian–Brews and Castagne–Vapaille methods, respectively. Additionally, the C/G–V characteristics were corrected before irradiation and after 60 kGy doses by considering the effects of Rs. These calculations show that Rs is more effective especially in the accumulation region and therefore, it must be considered in the calculations. All these results have indicated that MS-type SDs with (ZnO–PVA) polymer interfacial layer are very sensitive to gamma-irradiation. Hence, they can be successfully used as MPS-type detectors instead of MIS/MOS-type detectors. Hence, they can be successfully used as MPS-type detectors instead of MIS/MOS-type detectors, since polymer layers can be easily grown compared to insulator/oxide layers. Also, they are cheaper, lighter, more flexible, and require low energy consumption. In conclusion, it can be said that although all parameters were affected by gamma-irradiation, no significant defect/deterioration was observed in applied dose range which would hinder the operation of these MPS-type SDs.