Low-temperature synthesis of conducting boron-doped nanocrystalline silicon oxide thin films as the window layer of solar cells

Low-temperature synthesis of highly transparent conducting B-doped (p-type) nc-SiOX:H films has been pursued by 13.56 MHz plasma-CVD, using a combination of SiH4, CO2 and B2H6, diluted by H-2 and He. Higher substrate temperature (T-S) encourages nanocrystallization in B-doped nc-SiOX:H network by reducing bonded H-content, while bonded O-content also reduces simultaneously. At optimized T-S = 150 degrees C, p-nc-SiOX:H film having an optical band gap similar to 1.98 eV, high conductivity similar to 0.18 S cm(-1), has been obtained via dopant-induced escalation of the electrically active carriers at a deposition rate similar to 5.3 nm/min. The p-nc-SiOX:H film appears as a promising window layer for the top sub-cell of multi-junction silicon solar cells. A single-junction nc-Si:H based p-i-n solar cell of efficiency (eta) similar to 7.14% with a current-density (J(SC)) similar to 14.18 mA/cm(2), reasonable fill-factor (FF) similar to 66.2% and open-circuit voltage (V-OC) similar to 0.7606 V has been fabricated, using the optimum p-type nc-SiOX:H as the window layer deposited at T-S = 150 degrees C.