| Summary: | 碩士 === 國立中山大學 === 物理學系研究所 === 101 === In this thesis, first we use the program AMPS-1D (Analysis of Microelectronic and Photonic Structures) developed by the Pennsylvania State University to simulate the electrical performance of p-i-n InGaN solar cells. We change the Indium composition of the intrinsic layer from 5% to 35%. When the Indium composition is 20%, we get better energy conversion efficiency 5.777%.
We have grown InGaN p-i-n solar cell on n-type silicon (111) wafer by plasma assisted molecular beam epitaxy (PA-MBE) with an Al diffused p-type surface. In order to reduce the lattice mismatch between Si and GaN, a thin AlN was grown as a buffer layer. When we grow AlN buffer layer, the surface of Si was diffused by Al to form p-type Si. It forms a p-n junction with n-type Si substrate. Then we grow n-type GaN layer, intrinsic InGaN layer and p-type GaN layer to form the structure of tandem solar cell. From XRD measurement, we can observe the sample quality and the indium composition of InGaN layer. Then we do process for samples. First, we define the size of mesa by photolithography, wet etching and inductive coupled plasma etching. Then we evaporate transparent conductive layer (TCL), top contact and rear contact by dual e-beam evaporator. We measure the I-V curve of the devices by the solar simulator under 1 sun AM1.5G condition to observe the open circuit voltage, short circuit current, fill factor and energy conversion efficiency. We measure the external quantum efficiency of the devices by incident photon conversion efficiency (IPCE) and observe the photoelectric conversion efficiency of the devices at different wavelength. By these measurements, we discuss the effect of the devices by different grid lines spacing of p-type contact and different thickness of substrate. For different grid lines spacing of p type metal contact, it affects the short circuit current density. It has higher short current density for the lower metal contact shading. The metal contact shading is lower, the external quantum efficiency is higher. The maximum external quantum efficiency is 33% at the wavelength of 690 nm. By decreasing the substrate thickness reduced the recombination of carriers,
the open circuit voltage increase from 0.374 V to 0.494 V. Decreasing the substrate thickness also reduces the series resistance, it increases the fill factor.
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