Loading...
Please wait, while we are loading the content...
Similar Documents
Separation-rate improvement of epitaxial lift-off for III-V solar cells
| Content Provider | Semantic Scholar |
|---|---|
| Author | Wu, Fan-Lei Kao, Yu-Cheng Horng, Ray-Hua |
| Copyright Year | 2015 |
| Abstract | Thin-film III-V semiconductor solar cells have a number of advantages compared with other types of solar cells. For example, tuning the bandgap of III-V compound materials to match the solar spectrum gives the resulting solar cells unsurpassed conversion efficiencies. The virtues of these devices notwithstanding, the semiconductor substrate used in fabricating them is expensive, which adds to their cost. A method known as epitaxial lift-off (ELO) enables substrate reuse, which enhances affordability.1 However, the technique relies on hydrofluoric acid (HF) solution, a popular chemical etchant, and long-term exposure to the etchant increases the surface roughness of either the epilayer (i.e., the thin film containing the device) or the substrate. This roughness in turn hinders both substrate reuse and the performance of the solar cells. To solve this problem, various chemical fluids have been proposed to clean the substrate and modify the surface structure.2 But chemical cleaning is difficult to control because it is isotropic (that is, it etches at the same rate in every direction). A gallium arsenide (GaAs) solar cell on a (100) GaAs substrate consists of a 0.2 m-thick GaAs buffer layer, a 0.2 m-thick indium gallium phosphide (InGaP) etching stop layer, a 3 mthick GaAs buffer layer, a 20nm-thick aluminum arsenide (AlAs) sacrificial layer, and a 2.6 m-thick GaAs device epilayer. For ELO to be practical, etching time needs to be fast. However, arsine (AsH3) bubbles formed during the ELO process are known to obstruct the etching slits and prevent the AlAs sacrificial layer from reacting with the HF solution. Previous research3 established that oxygen is required for chemical etching of AlAs in HF solution. Blocking of the etching slits by the AsH3 bubbles Figure 1. (a) Lateral etching rate for the aluminum arsenide (AlAs) sacrificial layer during solar cell fabrication using various hydrofluoric acid (HF) solution mixtures. (b) Photograph of the sample. H2O: Water. ACE: Acetone. IPA: Isopropanol. MA: Methanol. |
| File Format | PDF HTM / HTML |
| DOI | 10.1117/2.1201501.005726 |
| Alternate Webpage(s) | http://www.spie.org/documents/Newsroom/Imported/005726/005726_10.pdf |
| Alternate Webpage(s) | http://web.nchu.edu.tw/~led/005726_10(SPIE%20newsroom%20final).pdf |
| Alternate Webpage(s) | https://doi.org/10.1117/2.1201501.005726 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
