| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 106 === In this thesis, the A/B/A and B/A/B quantum well (QW) structures were fabricated by pulse-modulated plasma-enhanced chemical vapor deposition system with different hydrogen dilution ratio (R = H2/SiH4) of 25, 50 and 100. The quantum well (QW) structure was inserted in i2/n-layer of the hydroge-nated amorphous silicon p-i-n solar cell, the cell structure was TCO/p/i1/QW/i2/n. Effects of quantum well structure on p-i-n solar cells were investigated.
The quantum well structures were prepared with different hydrogen dilu-tion ratios, which were a combination of (A/B/A) and (B/A/B). The samples were divided into three groups, which were: (1) R: 25/50/25 (A/B/A) or R: 50/25/50 (B/A/B), (2) R: 50/100/50 (A/B/A) and R: 100/50/100 (B/A/B), (3) R: 25/100/25 (A/B/A) and R: 100/25/100 (B/A/B).
The film thickness and the diffraction pattern in the were analyzed using a transmission electron microscope. The open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and conversion efficiency() of the solar cells were measured by measuring the dark and photo current-voltage curves. The quantum efficiencies of solar cells were measured by an external quantum efficiency (EQE) instrument.
The results of the diffraction rings of quantum well structures shown that in (B/A/B) structure is clearer than in (A/B/A) structure. The results of the three groups samples shown that the QW structure deposited by higher total hydrogen dilution ratio had clear diffraction rings, indicating the higher crystalline in the film.
The short circuit current density, fill factor and conversion efficiency of the solar cells with A/B/A QW were higher than those with B/A/B QW. The solar cell with the lowest hydrogen dilution ratio (R: 25/50/25) has the highest short-circuit current density and conversion efficiency. Conversely, the solar cell with the highest hydrogen dilution ratio (R: 100/50/100) was the lowest short-circuit current density and conversion efficiency.
The EQE data shown that the quantum efficiency of solar cell with A/B/A QW was higher than that with B/A/B QW in the short wavelength range (300-650 nm).The B/A/B QW structure blocked the collection of electrons generated by short wavelength light. The quantum well structure deposited by high total hydrogen dilutions would block more photo generated electrons by short - wavelength light.
As the total hydrogen dilution ratio for the deposition of quantum well structure is increased, the crystallization ratio of the structure is increased, and the collection of photo generated electrons has a high blocking effect.
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