Laser Annealing of Semiconductor Electrodeposited Reactants


CALL: 2010

DOMAIN: MS - Materials, Physics and Engineering





HOST INSTITUTION: University of Luxembourg

KEYWORDS: thin-film photovoltaics, annealing, defects, grain structure, laser, rapid thermal processing, rapid thermal annealing, electrodeposition, compound semiconductors, CuInSe2, Cu(In,Ga)Se2, CIS, CIGS

START: 2010-10-15

END: 2013-10-14


Submitted Abstract

The scientific objective of this proposed research is to investigate the effects of pulsed laser irradiation on modifying the structural, optoelectronic, and electronic defect properties of electrodeposited thin film chalcopyrite semiconductor photovoltaic materials. Laser irradiation offers methods of heating selectively in the depth direction, for example allowing a thin film, which may be buried, to be annealed at high temperature while negligibly heating other layers. The high temperatures achievable with ns laser annealing allow high local atom mobility over short distances but only for short times, for example annealing point defects while minimizing evaporative loss of high vapor pressure species. This proposed international collaboration draws on the complementary strengths of the two groups to address this objective: Dr. Scarpulla is an expert on pulsed laser processing of compound semiconductors and Dr. Dale is an expert on electrodeposition of chalcopyrite-derived semiconductors for photovoltaics. This proposal is based on promising results from a preliminary study carried out via an unfunded collaboration. This preliminary investigation has demonstrated desirable structural and phase changes in electrodeposited CIS films as a result of pulsed UV excimer laser irradiation. Previous reports have established that ns pulsed UV laser irradiation of evaporated Cu(In,Ga)Se2 (CIGS) films can improve the material properties and increase photovoltaic cell performance [1-4]. Also, annealing electrodeposited CuInSe2 (CIS) precursor films with a rastered visible laser can result in similar composition, phase, and structure to furnace annealing [5]. We propose to investigate two hypotheses about the combined electrodeposition and pulsed laser annealing (ED-PLA) of electrodeposited chalcopyrite films for photovoltaics using pulsed 248, 532, and 1064 nm lasers: Hypothesis 1 – Relatively-high total fluence nanosecond pulsed laser annealing is effective at annealing electrodeposited thin film precursors to synthesize the desired crystalline semiconductor phase having photovoltaic properties. Hypothesis 2 – Relatively low total fluence pulsed laser annealing is effective in reducing electronic and structural defects in previously-annealed chalcopyrite films.The fundamental scientific understanding of PLA of compound semiconductor photovoltaics could then be used to guide improvements in photovoltaic materials and solar cell fabrication processes. ED-PLA represents an entire non-vacuum technique of photovoltaic absorber layer synthesis using cheap and scalable processes; therefore this concept may enable solar cell manufacturing at competitive cost and performance. This collaborative effort between groups with complementary areas of expertise will give valuable international research experience to participating students and facilitate effective knowledge transfer and between a leading chalcopyrite PV material defects group and a beginning US PV research group. This project will also support the early careers of two young investigators. Both groups are also working in the rapidly-developing field of earth-abundant and environmentally-benign materials such as Cu2ZnSnS4 (CZTS) for photovoltaics. As a service to the international thin film PV community and the subgroup working in the aforementioned field, we propose to develop and maintain an online compilation of publications and materials data from these fields. By compiling useful information and publications in one place, progress will be accelerated in these rapidly developing and highly important fields.

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