Seong Won Kwon

Inclusion of nanosized silicon grains in hydrogenated protocrystalline silicon multilayers and its relation to stability

Photoluminescence and Fourier transform infrared spectroscopy measured at room temperature produce strong evidence that nanosized silicon (nc-Si) grains embedded in hydrogenated protocrystalline silicon (i-pc-Si:H) multilayers. Thus, we propose the structure of the i-pc-Si:H multilayer possessing isolated nc-Si grains and their wrapping layers with a high hydrogen concentration embedded in highly hydrogen-diluted sublayers. The isolated nc-Si grains may act as radiative recombination centers of photoexcited carriers, and hence suppress the photocreation of dangling bonds caused by the nonradiative recombination in amorphous silicon matrix. Because of the repeatedly layered structure, the i-pc-Si:H multilayers have a fast light-induced metastability with a low degradation.

Development of a rapidly stabilized protocrystalline silicon multilayer solar cell

We develop a rapidly stabilized pin-type thin film solar cell with a low degradation by combining a p-type hydrogenated amorphous silicon-carbide (p-a-SiC:H) double layer structure and an alternately hydrogen-diluted protocrystalline silicon (pc-Si:H) multilayer absorber. The p-a-SiC:H double layer structure increases overall initial parameters by reducing recombination at the p/i interface. After 12 h standard light irradiation, we achieve a stabilized efficiency of 9.0% without using any back reflector. Nano-sized silicon grains embedded in regularly arranged highly hydrogen-diluted sublayers of the pc-Si:H multilayer suppress the photocreation of dangling bonds in a amorphous silicon matrix acting as radiative recombination centres of photoexcited carriers.

Highly and rapidly stabilized protocrystalline silicon multilayer solar cells

We have developed highly stabilized (p-i-n)-type protocrystalline silicon ( pc -Si:H) multilayer solar cells. However, the source of the superior light-induced stability of the pc-Si:H multilayer absorbers compared to conventional amorphous silicon (a-Si:H) absorbers remains unclear. Photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy measured at room temperature produce strong evidence that nano-sized silicon grains embedded in regularly arranged highly H 2 -diluted sublayers suppress the photocreation of dangling bonds. To achieve a high conversion efficiency, we applied a double-layer p-type amorphous siliconcarbon alloy (p-a-Si 1-x C x :H) structure to the pc -Si:H multilayer solar cells. The less pronounced initial short wavelength quantum efficiency variation as a function of bias voltage, and the wide overlap of dark current - voltage ( J D -V ) and short-circuit current - open-circuit voltage (J sc -V oc ) characteristics prove that the double p-a-Si 1-x C x :H layer structure successfully reduces recombination at the p/i interface. Thus, we achieved a highly stabilized efficiency of 9.0 % without any back reflector.

Light-Soaking Behaviors of the Protocrystalline Silicon Multilayer : Origin of the Rapid Stabilized and Annealing Behavior

Protocrystalline silicon (pc-Si:H) multilayer is very promising owing to its rapid stabilization and fast annealing effect. In this paper, we suggest the microstructure factor as a figure of merit for evaluating light-soaking behavior of the pc-Si:H multilayers with different depositions. Furthermore, we investigate the annealing characteristics of the pc-Si:H multilayer solar cell

Deposition of device quality /spl mu/c-Si:H films by hot-wire CVD for solar cell applications

This paper presents deposition and characterizations of microcrystalline silicon (/spl mu/c-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below 300 degC . The SiH/sub 4/ concentration [F(SiH/sub 4/)/(SiH/sub 4/)+F(H/sub 2/)] is critical parameter for the formation of Si films with microcrystalline phase. At 6.3% of silane concentration, deposited intrinsic /spl mu/c-Si:H films show sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type /spl mu/c-Si:H films deposited by hot-wire CVD also shows good electrical properties by varying the rate of B/sub 2/H/sub 6/ to SiH/sub 4/ gas. The solar cells with structure of Al/nip /spl mu/c-Si:H/TCO/glass was fabricated with single chamber hot-wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.