Electrical properties of Cr/Si Schottky diodes

Cr/Si metal semiconductor (MS) contacts were prepared on chemically cleaned n-Si(100) and p-Si(111) substrates by using electron-beam evaporation method. Produced MS structures were examined by dc current-voltage characteristic under various constant temperatures infer both fundamental diode parameters (ideality factor, barrier height) and current flow mechanism through determining activating energy. Moreover, I-V characteristics were also investigated under dark and light conditions at room temperature so that photovoltaic behavior of the structures can be studied. The frequency/temperature dependent ac capacitance-voltage (C-V) characteristic of Cr/Si Schottky diodes were reported and doping density and barrier height of the structure were obtained from the slope and its intercept on the voltage axis of 1/C2 vs VG plot, respectively. As a step of study, Cr/Si Schottky diodes were annealed at different temperatures (400-500-600ºC) in order to increase their performance and electrical/photovoltaic effects of this act were observed.Extracted barrier height from I-V and C-V curves were compared which exhibited decline behavior for the first one and increasing attitude fort he second as temperature increases, respectively. Specifically, the variates of barrier height of Cr/n-Si extracted from I-V curves, was in the range of 0.87-1.08 eV, whereas the ideality factor lied between 1.65 to 1.14 for the studied temperature interval (300-380K). Similarly, for Cr/p-Si, the range were in between 0.85-1.05 eV and 1.63-1.46, respectively. On the other hand, barrier height obtained from C-V curves were consistent with the ones from I-V curves. Remarkably, annealing (heat treatment) deteriorate the diode parameters unexpectedly.The Schottky contacts? at hand have rectifying features, determined from I-V measurement under dark condition. As current flow mechanism, two bias regions were identified. Though different current flow mechanism exist in low applied bias voltage side (namely, Schottky emission for Cr/p-Si junction and ohmic mechanism for Cr/n-Si), SCLC was the common actual mechanism for both junctions at high bias voltage region.After examining the I-V characteristics of pre-annealing Cr/Si diodes in light condition, they exhibited good photovoltaic parameters. The best photovoltaic parameters were exposed by Cr/p-Si MS contact (Isc=44.5 ?A, Voc=370 mV). The best post-annealing photovoltaic parameter was shown by Cr/p-Si MS contact which was annealed at 600ºC (Isc=138.8 ?A, Voc=268 mV).