title: Wide range bandgap modulation based on ZnO-based alloys and fabrication of solar blind UV detectors with high rejection ratio.
abstract: Theoretical calculations on formation energies of MgZnO, BeZnO and BeMgZnO alloys are presented. The ternary alloy MgZnO (BeZnO) is found to be unstable with high Mg (Be) contents. However, the quaternary system BeMgZnO is predicted to be stable with small Be/Mg atom ratio. Subsequently, a wurtzite Be0.17Mg0.54Zn0.29O alloy with a bandgap of 5.15 eV has been acquired experimentally. Its bandgap is in the middle of solar blind region and thus it is an ideal material for realizing a high rejection ratio solar blind ultraviolet (UV) detector, which has long been a problem. A metal-semiconductor-metal (MSM) structured solar blind UV detector based on this material is then fabricated, realizing a much higher rejection ratio than reported MgZnO-based detectors. One more interesting thing is, as a complicated quaternary system, BeMgZnO can maintain its crystal quality in a wide compositional range, which is not happening in MgZnO and BeZnO. To get some microscopic insight into the Be-Mg mutual stabilizing mechanism, more calculations on the lattice constants of BeZnO and MgZnO alloys, and the coordination preference of Be ions in alloy were conducted. The a-axis lattice compensation and 4-fold coordination preference of Be atom are confirmed the major origins for Be-Mg mutual stabilizing in ZnO lattice.
authors.affiliation: State key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University , Guangzhou 510275, China.
authors.forename: Longxing
authors.initials: L
authors.lastname: Su
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Dingyu
authors.initials: D
authors.lastname: Yong
authors.forename: Mingming
authors.initials: M
authors.lastname: Chen
authors.forename: Xu
authors.initials: X
authors.lastname: Ji
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Su
authors.forename: Xuchun
authors.initials: X
authors.lastname: Gui
authors.forename: Bicai
authors.initials: B
authors.lastname: Pan
authors.forename: Rong
authors.initials: R
authors.lastname: Xiang
authors.forename: Zikang
authors.initials: Z
authors.lastname: Tang