Malaysian Journal of Analytical Sciences Vol 19 No 6 (2015): 1274 - 1283

 

 

 

Pulsed Laser Interactions with Silicon Nanostructures

in Emitter Formation

 

(Interaksi Denyutan Laser dengan Nano-Struktur Silikon dalam Pembentukan Pemancar)

 

Victor Lim Chee Huat*, Cheow Siu Leong, Kamaruzzaman Sopian, Saleem Hussain Zaidi

 

Solar Energy Research Institute (SERI),

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

 

*Corresponding author: victorlimch@yahoo.com

 

 

Received: 4 January 2015; Accepted: 29 September 2015

 

 

Abstract

Silicon wafer thinning is now approaching fundamental limits for wafer thickness owing to thermal expansion mismatch between Al and Si, reduced yields in wet-chemical processing as a result of fragility, and reduced optical absorption. An alternate manufacturing approach is needed to eliminate current manufacturing issues. In recent years, pulsed lasers have become readily available and costs have been significantly reduced. Pulsed laser interactions with silicon, in terms of micromachining, diffusions, and edge isolation, are well known, and have become industrial manufacturing tools. In this paper, pulsed laser interactions with silicon nanostructures were identified as the most desirable solution for the fundamental limitations discussed above. Silicon nanostructures have the capability for extremely high absorption that significantly reduces requirements for laser power, as well as thermal shock to the thinner wafer. Laser-assisted crystallization, in the presence of doping materials, leads to nanostructure profiles that are highly desirable for sunlight absorption. The objective of this paper is the replacement of high-temperature POCl₃ diffusion by laser-assisted phosphorus layers. With these improvements, complete low-temperature processing of thinner wafers was achievable with 3.7 % efficiency. Two-dimensional laser scanning was proved to be able to form uniformly annealed surfaces with higher fill factor and open-circuit voltage.

 

Keyword: pulsed laser interactions, silicon nanostructures, laser-assisted crystallization

 

Abstrak

Penipisan wafer silikon pada masa ini sudah mendekati had asas ketebalan wafer kerana ketakserasian pengembangan terma antara Al dan Si, pengurangan hasil dalam proses kimia basah adalah disebabkan oleh kerapuhan, dan pengurangan penyerapan optik. Pendekatan pembuatan adalah diperlukan supaya mengatasi masalah pembuatan semasa. Kebelakangan ini, denyutan laser sudah tersiap sedia dan kos telah ternyata berkurang. Interaksi denyutan laser dengan silikon dari segi pemesinan mikro, pembuaran, dan pengasingan tepi sudah diketahui umum dan menjadi alat pembuatan industri. Dalam makalah ini, interaksi denyutan laser dengan nano-struktur silikon telah dikenal pasti sebagai penyelesaian paling dikehendaki kepada had asas yang telah dibincangkan diatas. Nano-struktur silikon mempunyai kebolehan penyerapan yang teramat tinggi sehingga mampu mengurangkan kuasa laser diperlukan dan juga renjatan terma kepada wafer yang lebih nipis. Penghabluran bantuan laser dengan kewujudan bahan tambah telah membawa kepada pembentukan nano-struktur yang mempunyai penyerapan cahaya matahari yang lebih dikehendaki. Objektif makalah ini telah dikenal pasti sebagai pengantian pembauran POCl₃ suhu tinggi oleh lapisan forforus bantuan laser. Dengan kemajuan ini, pemprosesan wafer yang lebih nipis pada suhu rendah secara menyeluruh telah dicapai dengan kecekapan 3.7%. Dua dimensi imbasan laser telah dibuktikan dapat membentuk permukaan lindapan yang seragam dengan faktor isi dan voltan litar buka yang lebih tinggi.

 

Kata kunci: interaksi denyutan laser, nano-struktur silikon, penghabluran bantuan laser

 

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