Presentation Information
[9a-E217-9]Improvement of photovoltaic properties in ZnTe solar cells by Al diffusion into P-doped ZnTe layers grown by MBE
〇(PC)Muhamad Mustofa1, Katsuhiko Saito1, Qixin Guo1, Tooru Tanaka1 (1.Saga Univ.)
Keywords:
Molecular Beam Epitaxy,ZnTe based Solar cell,Al-diffusion in ZnTe
Intermediate-band solar cells (IBSCs) are considered a promising approach for achieving high solar energy conversion efficiencies [1]. ZnTe1-xOx (ZnTeO) alloys are potential candidates for absorber materials in IBSC due to the formation of O-derived intermediate band (IB (E-)) below the conduction band (CB (E+)) edge of ZnTe [2]. In ZnTeO-based IBSC, the good conductivity control of p-type ZnTe epitaxial layer is important for boosting the carrier collection efficiency of the device. Our previous studies on molecular beam epitaxial (MBE) growth of P-doped ZnTe using a cracked Zn3P2 source demonstrated good controllability of the P concentration, ranging from 8.3 ´ 1016 cm-3 to 4.8 ´ 1017 cm-3 with increasing Zn3P2 flux [3]. A heterojunction solar cell using high-quality P-doped ZnTe as the absorber layer exhibited a power conversion efficiency (η) of 3.7% [3]. Although this is the highest efficiency reported for ZnTe solar cells, further improvement is still required to enhance device performance. In this study, a thin Al-diffused layer was introduced into the surface of the P-doped ZnTe to form a very thin n-type ZnTe layer and improve carrier collection and interface properties between P-doped ZnTe and ZnS layers, which will lead to an increase in the power conversion efficiency.