High quality crystalline ZnO buffer layers on sapphire (001) by pulsed laser deposition for III–V nitrides

Abstract

ZnO thin films with near perfect crystallinity have been grown epitaxially on sapphire ͑001͒ by pulsed laser deposition technique. The-rocking curve full width at half-maximum of the ZnO͑002͒ peak for the films grown at 750°C, oxygen pressure 10 Ϫ5 Torr was 0.17°. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2%-3% in the near-surface region (ϳ2000 Å). The atomic force microscopy revealed smooth hexagonal faceting of the ZnO films. It has been possible to deposit epitaxial AlN films of thickness 1000 Å on epi-ZnO/sapphire. Excellent crystalline properties of these epi-ZnO/sapphire heterostructures are, thus, promising for lattice-matched substrates for III-V nitride heteroepitaxy and optoelectronics devices.

Preparation of Highly Textured ZnO Thin Films by Pulsed Electron Deposition

“…[1][2][3][4][5][6][7][8][9] Many approaches have been developed to fabricate ZnO nanostructures and high quality thin films for applications in a diversity of fields, such as molecular beam epitaxy (MBE), 10) metal-organic chemical vapor deposition (MOCVD), 11) pulsed laser deposition (PLD), 12) and physical vapor transportation. 13) Mostly ZnO thin films suffer from the crystal quality and various kinds of defects, such as zinc interstices (Zn i ), zinc vacancies (V Zn ), oxygen interstices (O i ), and oxygen vacancies (V O ).…”

Investigation of laser-ablated ZnO thin films grown with Zn metal target: A structural study

“…ZnO is an oxide that can be grown, as a thin film, by many deposition techniques including chemical vapor deposition, radio frequency sputtering, magnetron sputtering, solgel, ion-beam assisted, molecular beam epitaxy and pulsed laser deposition [9][10][11][12][13][14][15][16] . The zinc oxide shows a n-type conduction, without intentional doping, and crystallizes in a wurtzite structure that contains large voids that can easily accommodate interstitial atoms.…”

Oxygen pressure-tuned epitaxy and optoelectronic properties of laser-deposited ZnO films on sapphire

“…[1][2][3][4][5][6][7] It has higher exciton binding energy ͑60 meV for ZnO versus 28 meV for GaN͒ and higher optical gain ͑300 cm Ϫ1 ͒ than GaN ͑100 cm Ϫ1 ͒ at room temperature. 1 Moreover, recent reports on externally pumped lasing in epitaxial ZnO thin films by Kawasaki et al 2 and Bagnall et al 3 have stimulated great interest in ZnO material for realizing efficient, excitonic UV blue lasers at room temperature.…”

“…12,13 The films were grown on sapphire ͑0001͒ at an optimized growth temperature of 750°C. 5 Thin-film growth was carried out at various oxygen background (O 2 ) pressures ranging from 10 Ϫ5 to 10 Ϫ1 Torr. In some cases, initial stages of growth ͑100-500 Å͒ were carried out at a growth temperature of 750°C and O 2 pressure of 10 Ϫ4 Torr in order to grow high-quality epilayers, and then the O 2 pressure was increased to 10 Ϫ1 Torr.…”