GaAs/AlGaAs Nanowire Array Solar Cell Grown on Si with Ultrahigh Power-per-Weight Ratio

Abstract

Here we demonstrate a more effective use of III−V photoconversion material to achieve an ultrahigh power-per-weight ratio from a solar cell utilizing an axial p-i-n junction GaAs/AlGaAs nanowire (NW) array grown by molecular beam epitaxy on a Si substrate. By analyzing single NW multicontact devices, we first show that an n-GaAs shell is self-formed radially outside the axial p-and i-core of the GaAs NW during n-core growth, which significantly deteriorates the rectification property of the NWs in the axial direction. When employing a selective-area ex situ etching process for the n-GaAs shell, a clear rectification of the axial NW p-i-n junction with a high on/off ratio was revealed. Such a controlled etching process of the self-formed n-GaAs shell was further introduced to fabricate axial p-i-n junction GaAs NW array solar cells. Employing this method, a GaAs NW array solar cell with only ∼1.3% areal coverage of the NWs shows a photoconversion efficiency of ∼7.7% under 1 Sun intensity (AM 1.5G), which is the highest achieved efficiency from any single junction GaAs NW solar cell grown on a Si substrate so far. This corresponds to a power-perweight ratio of the active III−V photoconversion material as high as 560 W/g, showing great promise for high-efficiency and lowcost III−V NW solar cells and III−V NW/Si tandem solar cells.

Conventional Polymer Solar Cell using Low Temperature Sol-gel ZnO Thin Film

“…태양전지는 크게 무기태양전지와 유기 태양전지로 나눌 수 있다. 무기태양전지는 실리콘을 주재료로 사용하는 실리콘 태양전지 (단결정, 다결정, 비정질) 와 CdTe, CIGS, GaAS 등 화합물 반도체를 이용한 태양전지가 있다 1) . 이러한 무기태양전지가 지금의 태양전지 시장의 대부분을 차지하고 있으며 이들의 전력변환 효율은 높 은 편이다 2,3) .…”

Nanowire-based synaptic devices for neuromorphic computing

“…Compared with 2D materials, NWs are more suitable for high integration and low power consumption synaptic devices. Nowadays, NWs have been integrated into diodes [30], field effect transistors (FETs) [31], memories [32], photodetectors [33], solar cells [34], and synaptic devices [19,23,35]. Based on the basic synaptic functionalities of NW-based synaptic devices, NWs can be constructed for neuromorphic computing.…”

GaAs/GaInP nanowire solar cell on Si with state-of-the-art Voc and quasi-Fermi level splitting

“…10 Given that ternary III-V compositions are difficult to control and less studied than binary compounds, most efforts in the photovoltaics community have been focused on fabricating GaAs-based NW solar cells. [11][12][13][14][15] To date, the best GaAs NW on Si tandem solar cell has reached an efficiency of 11.4%, 16 while the best single junction GaAs NW solar cell directly grown on Si has demonstrated an efficiency of 7.7%. 15 So far, the performances of GaAs NW solar cells grown on Si have been primarily limited by their open-circuit voltage (V OC < 0.62 V for NW array solar cells 15 ).…”

“…[11][12][13][14][15] To date, the best GaAs NW on Si tandem solar cell has reached an efficiency of 11.4%, 16 while the best single junction GaAs NW solar cell directly grown on Si has demonstrated an efficiency of 7.7%. 15 So far, the performances of GaAs NW solar cells grown on Si have been primarily limited by their open-circuit voltage (V OC < 0.62 V for NW array solar cells 15 ). Note that in the same study, a V OC of 0.77 V was obtained for a single NW solar cell, however the direct comparison with NW array solar cells is difficult and should consider the fact that a single NW absorbs light from an area, the absorption crosssection, much larger than its geometrical cross-section.…”

“…10 Given that ternary III–V compositions are difficult to control and less studied than binary compounds, most efforts in the photovoltaics community have been focused on fabricating GaAs-based NW solar cells. 11–15…”