Donor-acceptor-pair photoluminescence in Ga-doped ZnO thin films grown by plasma-assisted molecular beam epitaxy

作者：Yang Z; Liu J L^*

来源：Journal of Vacuum Science and Technology B, 2010, 28(3).

DOI：10.1116/1.3368543

• carrier density
• doping
• gallium
• II-VI semiconductors
• molecular beam epitaxial growth
• photoluminescence
• plasma materials processing
• semiconductor thin films
• spectral line shift
• wide band gap semiconductors
• zinc compounds

Three dominant emission lines: neutral Ga-Zn donor bound exciton I-8 (3.359 eV); ionized Ga-Zn donor bound exciton I-1 (3.368-3.371 eV), and donor-acceptor-pair (DAP) I-DA (3.313-3.321 eV) were observed in the 9 K photoluminescence (PL) spectra from a series of Ga-doped ZnO thin films with electron carrier concentration (n) ranging from 3.6x10(18) to 3.5x10(19) cm(-3). As n increases, the dominant PL line changes from I-1 to I-DA, and finally to I-8. Characteristic blueshifts of I-DA PL lines were observed with increasing n, with increasing excitation power in power-dependent PL spectra, and with increasing temperature in temperature-dependent PL spectra. The experimental results of I-DA lines in Ga-doped ZnO are generalized to a proposed model to explain the possibilities of the widely observed 3.30-3.32 eV PL lines in ZnO as DAP transitions, which are associated with a shallow donor (e.g., Ga, Al, In, H, etc) with an ionization energy of similar to 44-65 meV and a deep acceptor V-Zn with an ionization energy of similar to 180 meV.

• 出版日期2010-5