| Popis: |
The electrical properties of hydrogenated amorphous silicon (a‐Si:H) metal–semiconductor–metal (MSM) devices are investigated as a function of Si bombardment dose prior to and after annealing. We observe that conduction in unbombarded devices is surface-barrier controlled whereas it is bulk controlled in bombarded devices. The resistance decreases with bombardment dose in a manner consistent with increased hopping conductivity in highly damaged structures. A relative permittivity of between 8 and 12, depending on dose, was calculated from experimental Poole–Frenkel plots for bombarded devices. These values compare closely with the theoretical relative permittivity for amorphous silicon of 11.7 and confirm that conduction is by Poole–Frenkel mechanism. For bulk-controlled conduction, we observe an increase in the zero-field Coulombic trap barrier height with decreasing dose, ranging from 0.53 for a Si dose of 5×1013cm−2 to 0.89 for a dose of 2×1012cm−2. We attribute this to a decrease in the concentration ... |
