Vapor Transport Deposition and Characterization of Polycrystalline CdTe Solar Absorbers

Abstract

Vapor transport deposition is being developed for high-rate synthesis of CdTe thin films. Films have been deposited at rates in excess of 20 μm/min. Thegrowth ratedependenceon source temperature yielded an apparent activation energy of 42 kcal/mol, in good agreement with the theoretical value for CdTe sublimation (45.7 kcal/mol). For substrate temperatures greater than 400°C the rate limiting step was resublimation. This phenomenon had a dramatic influence on morphology, although x-ray diffraction of all films indicated a strong (111) orientation. A preliminary device optimization investigating the effect of CdTe deposition temperature, post-deposition CdCl2 anneal parameters, alternative back contacts, and high-resistance buffer layers yielded a best cell with efficiency of 9.8% (704 mV Voc, 21.0mA/cm2 Jsc, 66% FF).

Studies of Basic Electronic Properties of CdTe-Based Solar Cells and Their Evolution During Processing and Stress: Final Technical Report, 16 October 2001 - 31 August 2005

“…Cells were manufactured using standard procedures at NREL [32], and CSM [33,34], detailed elsewhere. Addition of an HRT layer was the only intentional variation made at each institution.…”

Simulation for deposition of cadmium telluride thin films in hot wall epitaxial system using Monte Carlo technique

“…In order to facilitate new applications of thin films, better understanding and control of the deposition processes are required. Numerous approaches [1][2][3][4][5][6][7][8][9][10] for deposition of thin film materials including hot wall epitaxy designs were attempted during the 1970s and 1980s. Computer simulations can often complement the information obtained from experiments.…”