Spectral change of intermediate band luminescence in GaP:N due to below-gap excitation: Discrimination from thermal activation

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• 作者：N. Kamata ; M. Suetsugu ; D. Haque ; S. Yagi ; H. Yaguchi ; F. Karlsson and P. O. Holtz
• 刊名：physica status solidi (b)
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：254
• 期：2
• 全文大小：1614K
• ISSN：1521-3951

文摘

As an intermediate band (IB) originating from discrete nitrogen (N) levels is formed in GaP:N with increasing N concentration, GaP_1−xN_x alloy is considered to be a promising candidate for IB-type solar cells. We studied the IB luminescence of a GaP_1−xN_x with 0.56% N and detected carrier recombination (CR) levels by superposing a below-gap excitation (BGE) light of 1.17 eV. We resolved a high-energy component of 2.15 eV in the IB luminescence, I_high, from total luminescence intensity I_all. With increasing the BGE density at fixed temperature of 5 K, the amount of decrease in I_high was distinctly smaller than that of simple temperature rise without the BGE at the same I_all value. We conclude that the observed intensity change of the IB luminescence due to the BGE comes not from thermal activation, but from optical excitation among the IB, conduction band, and CR levels in GaP_1−xN_x. It is of primal importance to understand CR levels toward determining their origins and eliminating them for realization of efficient IB-type solar cells.