Electronic characterization of Al/PMMA[poly(methyl methacrylate)]/p-Si and Al/CEP(cyanoethyl pullulan)/p-Si structures

Thin films of poly(methyl methacrylate) (PMMA) and cyanoethyl pullulan (CEP) were prepared by spin coating on p-Si substrate. Capacitance–voltage (C–V) and current–voltage (I–V) behavior of the aluminum/PMMA/p-Si and Al/CEP(cyanoethyl pullulan)/p-Si MIS (metal–insulator–semiconductor) structures was studied at various frequencies ranging from 20 kHz to 1 MHz and for a bias voltage range of −50 V to +20 V. No hysteresis was observed in the C–V curve for both films as deposited and annealed (70–200 °C). Flat band voltage (VFB) of aluminum/PMMA/p-Si structure with as deposited films was about −15 V and increased up to −30 V with annealing. This suggested that a large amount of positive charge was generated in the film. Electronic properties of the annealed PMMA film at above glass transition temperature were degraded substantially with larger shift in flat band voltage, low dielectric constant and low breakdown voltage. Al/CEP(cyanoethyl pullulan)/p-Si showed VFB about −1 V for both as deposited or annealed film and CEP is more stable than PMMA. Frequency dependence of the electronic properties was also studied.