การศึกษาคุณสมบัติของอะมอร์ฟัสซิลิคอนเจอร์เมเนียมและการประยุกต์เป็นเซลล์แสงอาทิตย์ / ตุลา จูฑะรสก = A study on properties of amorphous silicon germanium and its application to solar cells / Tula Jutarosaga
The thesis reports the study on the growth of hydrogenated amorphous silicon germanium thin film (a-SiGe:H) by the glow discharge plasma CVD method using the gas mixture of SiH4, GeH4 and H2. It has been found that the optical energy gap of a-SiGe:H decreases from 1.59 eV to 1.14 eV when the gas flow rate ratio of GeH4/(SiH4+GeH4) is increased from 0.17 to 0.83. It has been found that the photoconductivity of a-SiGe:H having the optical energy gap of 1.5-1.6 eV could be improved by adding a large amount of H2 gas flow during the deposition of the films and using the substrate temperature of about 250 ํC. The resulting ratio of photoconductivity and dark-conductivity is as high as 10x10x10 - 10x10x10x10. The optimized a-SiGe:H have been applied to the active layer in the p-i-n junction solar cell. The open circuit voltage, short circuit current, fill factor and conversion efficiency obtained were 0.6 V, 25.8 mA/cm2, 36% and 5.6%, respectively. The double-junction solar cells consisting of an a-Si:H solar cell and a-SiGe:H solar cell have also been fabricated. The open circuit voltage, short circuit current, fill factor and conversion efficiency obtained were 1.25V, 12.7mA/cm2, 39% and 6.1%, respectively. The spectral response of the double-junction solar cell was broader than that of a conventional a-Si:H solar cell.
