Enhanced photo-sensitivity through an increased light-trapping on Si by surface nano-structuring using MWCNT etch mask
1 College of Electronics and Information, Kwangwoon University, Nowon-gu Seoul 139-701, South Korea
2 Institute of Nanoscale Science and Engineering, University of Arkansas, Fayetteville, AR 72701, USA
Nanoscale Research Letters 2011, 6:573 doi:10.1186/1556-276X-6-573Published: 31 October 2011
We demonstrate an enhanced photo-sensitivity (PS) through an increased light-trapping using surface nano-structuring technique by inductively coupled plasma (ICP) etching on multi-walled carbon nanotube (MWCNT) etch masked Si with hexamethyl-disilazane (HMDS) dispersion. In order for a systematic comparison, four samples are prepared, respectively, by conventional photolithography and ICP etching using MWCNT as a etch mask. MWCNT-etched Si with HMDS dispersion shows the highest RMS roughness and the lowest reflectance of the four. Two test device structures are fabricated with active regions of bare-Si as a reference and MWCNT etch masked Si with HMDS dispersion. The increased light-trapping was most significant at mid-UV, somewhat less at visible and less noticeable at infrared. With an ICP-etched Si using CNT HMDS dispersion, PS is very sharply increased. This result can lead to applications in optoelectronics where the enhancement in light-trapping is important.