New developments in ZnO materials and devices

We will examine a few of the outstanding new ZnO materials and device developments published in 2006. In the area of bulk crystal growth, high-quality 3-inch ZnO wafers grown by the hydrothermal method have become available, and Bridgman growth has also been developed. In the thin-film area, excellent ZnO layers have been grown by liquid-phase epitaxy. Other types of epitaxial material have also shown improvements, and the quantum Hall effect has now been observed, along with photoluminescence (PL) linewidths as low as 110 &mgr;eV. In the area of impurity characterization, radioactive-tracer methods have been used to make positive identifications of the PL donor-bound exciton lines I8 and I9, as due to Ga and In, respectively. Our understanding of the common impurity H has also advanced, because it is now known from both theory and experiment that interstitial H is not stable at room temperature. The same is true of the native interstitials, ZnI and OI. New results suggest that the common H-related shallow donor is probably multibonded H substitutional on an O site, and the ZnI-related shallow donor is probably a complex, such as ZnI-NO. In the important area of p-type ZnO, it has been demonstrated that Li and N co-doped material has a resistivity as low as 1 &OHgr;-cm and is stable for at least one year. Also, many groups were able to make thin-film and nanowire or nanorod p-n junction light emitting diodes (LEDs). Another very exciting development was the creation of an edge-emitting laser diode, from rows of n-ZnO nanocrystals on a p-GaN thin film. Electronic devices, including transparent transistors, also made great strides, producing record field-effect mobilities.

[1]  D. Ehrentraut,et al.  Fabrication of homoepitaxial ZnO films by low-temperature liquid-phase epitaxy , 2006 .

[2]  Yueguang Lu,et al.  Formation of p-type MgZnO by nitrogen doping , 2006 .

[3]  Marius Grundmann,et al.  Deep acceptor states in ZnO single crystals , 2006 .

[4]  Atsuo Yamada,et al.  Two-dimensional electron gas in Zn polar ZnMgO∕ZnO heterostructures grown by radical source molecular beam epitaxy , 2006 .

[5]  Pedro Barquinha,et al.  A Study on the Electrical Properties of ZnO Based Transparent TFTs , 2006 .

[6]  Eunice S. P. Leong,et al.  Directional edge-emitting UV random laser diodes , 2006 .

[7]  Jun Yuan,et al.  Control of p- and n-type conductivities in Li-doped ZnO thin films , 2006 .

[8]  Michael Uhrmacher,et al.  Unambiguous identification of the PL-I9 line in zinc oxide , 2007 .

[10]  Il-Kyu Park,et al.  UV Electroluminescence Emission from ZnO Light‐Emitting Diodes Grown by High‐Temperature Radiofrequency Sputtering , 2006 .

[11]  Gehan A. J. Amaratunga,et al.  High performance ZnO nanowire field effect transistor using self-aligned nanogap gate electrodes , 2006 .

[12]  Mitsuru Sato,et al.  Growth of 2 inch ZnO bulk single crystal by the hydrothermal method , 2005 .

[13]  Dirk Ehrentraut,et al.  Growth of MgxZn1-xO/ZnO Heterostructures by Liquid Phase Epitaxy , 2006 .

[14]  Federico Capasso,et al.  Broadband ZnO single-nanowire light-emitting diode. , 2006, Nano letters.

[15]  Paul Erhart,et al.  First-principles study of migration mechanisms and diffusion of oxygen in zinc oxide , 2006 .

[16]  D. C. Reynolds,et al.  Electrical properties of bulk ZnO , 1998 .

[17]  Z. P. Wei,et al.  The mechanism of formation and properties of Li-doped p-type ZnO grown by a two-step heat treatment , 2006 .

[18]  David C. Look,et al.  Local p-type conductivity in n-GaN and n-ZnO layers due to inhomogeneous dopant incorporation , 2006 .

[19]  Jianguo Lu,et al.  Low-resistivity, stable p-type ZnO thin films realized using a Li–N dual-acceptor doping method , 2006 .

[20]  E. Alves,et al.  Direct evidence for As as a Zn-site impurity in ZnO. , 2005, Physical review letters.

[21]  E. V. Kortunova,et al.  The first attempts of industrial manufacture of ZnO single crystals , 2005 .

[22]  Eunice S. P. Leong,et al.  UV Random Lasing Action in p‐SiC(4H)/i‐ZnO–SiO2 Nanocomposite/n‐ZnO:Al Heterojunction Diodes , 2006 .

[23]  P. Briddon,et al.  First-principles study of the diffusion of hydrogen in ZnO. , 2006, Physical review letters.

[24]  Karl Johnston,et al.  Identification of donor-related impurities in ZnO using photoluminescence and radiotracer techniques , 2006 .

[25]  D. Look,et al.  Evidence for native-defect donors in n-type ZnO. , 2005, Physical review letters.

[26]  Kee-Joo Chang,et al.  P-type doping with group-I elements and hydrogenation effect in ZnO , 2006 .

[27]  Paul Erhart,et al.  Diffusion of zinc vacancies and interstitials in zinc oxide , 2006 .

[28]  V. Walle,et al.  Hydrogen as a cause of doping in zinc oxide , 2000 .

[29]  N. H. Nickel.  Hydrogen migration in single crystal and polycrystalline zinc oxide , 2006 .

[30]  David C. Look,et al.  Donors and Acceptors in Bulk ZnO Grown by the Hydrothermal, Vapor-Phase, and Melt Processes , 2006 .

[31]  Steffen Ganschow,et al.  Bridgman-grown zinc oxide single crystals , 2006 .

[32]  K. Fleischer,et al.  Hydrogen local vibrational modes in zinc oxide. , 2003, Physical review letters.

[33]  D. C. Reynolds,et al.  Neutral-Donor-Bound-Exciton Complexes in ZnO Crystals , 1998 .

[34]  Byeong Yun Oh,et al.  Electroluminescence from ZnO nanowires in n-ZnO film/ZnO nanowire array/p-GaN film heterojunction light-emitting diodes , 2006 .

[35]  G. D. Watkins,et al.  Intrinsic defects in ZnO: A study using optical detection of electron paramagnetic resonance , 2006 .

[36]  Chris G. Van de Walle.  Hydrogen as a cause of doping in ZnO , 2001 .

[37]  C. H. Park,et al.  Doping by large-size-mismatched impurities: the microscopic origin of arsenic- or antimony-doped p-type zinc oxide. , 2004, Physical review letters.

[38]  Deren Yang,et al.  Electroluminescence from ZnO/n+-Si Heterojunction , 2007 .