Current‐voltage characteristics of n‐amorphous low‐pressure chemical vapor deposited silicon films on p‐crystalline silicon

Heterojunction devices have been fabricated by a low‐pressure chemical vapor deposition technique whereby n‐type amorphous or microcrystalline silicon films were grown on p‐type crystalline silicon substrates. Heterostructures produced under various conditions of thin film deposition were subjected to detailed I‐V curve analysis. It is seen that for amorphous‐crystalline heterojunctions the current transport is through tunneling in the low bias range and limited by electron‐hole recombination in the high bias range. For the microcrystalline‐crystalline junctions however, recombination current at the interface dominates the current transport process. Illuminated I‐V curves corresponding to films deposited at different substrate temperatures (Ts ) and dopant gas‐to‐silane ratios (R) show that the high values of the short‐circuit current (Isc), open‐circuit voltage (Voc ), and fill factor (FF) are achieved at values close to Ts ∼620 °C and R ∼4×10−3 in conformance with dark I‐V characteristic data.