Title :
The role of H2 dilution in the deposition of a-Si:H films and its effect on the solar cell degradation
Author :
Siamchai, Pavan ; Konagai, Makoto
Author_Institution :
Dept. of Electr. & Electron. Eng., Tokyo Inst. of Technol., Japan
Abstract :
The role of H2 dilution in the mercury-sensitized photochemical vapor deposition of a-Si:H film solar cells has been investigated by using D2 as a diluent instead of H2. The increase in the D content in the a-Si:H,D film with the D2/SiH4 dilution ratio indicated that the H 2 dilution could increase the atomic hydrogen concentration near the growth surface. In addition, the numerical model has been used to estimate the change in the dangling bonds density and energy level in the H2-diluted film by comparing with the temperature dependency of dark conductivity in initial and light-soaked states. It was found that the center level of the dangling bonds shifted toward the valence band edge as the bandgap of the film widened due to the H2 dilution. This shift in the dangling bonds level in the i layer resulted in the increase of open circuit voltage of a-Si:H solar cell with the light soaking time as confirmed by simulation and experimental results
Keywords :
CVD coatings; amorphous semiconductors; chemical vapour deposition; dangling bonds; deuterium; elemental semiconductors; energy gap; hydrogen; semiconductor device models; semiconductor device testing; semiconductor doping; semiconductor growth; semiconductor thin films; silicon; solar cells; H2 dilution; Si:H,D; a-Si:H film deposition; a-Si:H,D solar cells; atomic hydrogen concentration; bandgap; dangling bonds density; dark conductivity; energy level; growth surface; light soaking time; numerical model; open circuit voltage; photochemical vapor deposition; solar cell degradation; solar cell fabrication; valence band edge; Chemical vapor deposition; Conductive films; Conductivity; Energy states; Hydrogen; Numerical models; Photochemistry; Photovoltaic cells; State estimation; Temperature dependence;
Conference_Titel :
Photovoltaic Specialists Conference, 1996., Conference Record of the Twenty Fifth IEEE
Conference_Location :
Washington, DC
Print_ISBN :
0-7803-3166-4
DOI :
10.1109/PVSC.1996.564321
