Nitride and Oxide Based Nanowires Grown by Plasma-Assisted Molecular Beam Epitaxy
- PDF / 378,288 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 0 Downloads / 194 Views
0940-P13-33
Nitride and Oxide Based Nanowires Grown by Plasma-Assisted Molecular Beam Epitaxy Chito E Kendrick1,2, Damian Carder2,3, Pual Miller2,3, Roger J. Reeves2,3, Richard Tilley2,4, and Steven M. Durbin1,2 1 Electrical and Computer Engineering, University of Canterbury, Christchurch, 8004, New Zealand 2 MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand, New Zealand 3 Physics and Astronomy, University of Canterbury, Christchurch, 8004, New Zealand 4 School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 8001, New Zealand ABSTRACT The growth of nanostructured material continues to attract attention for a number of applications, including highly sensitive gas sensors (due to the increased surface area), and photonic crystals (which require arrays of nanostructures). Even though nanostructures can be formed through self-assembly, they often do not possess the high crystal quality of those grown using vapor liquid solid (VLS) techniques; also, with VLS the feature size and placement can be easily controlled. To achieve VLS growth, however, several parameters have to be considered specific to the material of interest. In this study, we examine VLS growth of both InN (infrared) and ZnO (ultraviolet) nanostructures. INTRODUCTION ZnO and InN are two semiconductor materials that have dominated recent publications. InN over the recent years has been a highly controversial material, due to the debate over the bandgap value—one of the most fundamental values used to characterize a semiconductor. Several groups have presented optical data showing both photoluminescence (PL) and optical absorption with features in the 0.7 – 1.0 eV region from molecular beam epitaxy (MBE) samples, compared to the previous bandgap value of 1.9 eV measured from an RF-sputtered sample using optical absorption [1-3]. The InGaN ternary system can therefore absorb light from 0.9 eV to 3.45 eV, allowing the possible fabrication of photovoltaic cells that could mimic the terrestrial solar spectrum [4]. InN also has a theoretical maximum mobility of 4400 cm2/Vs at 300 K (30,000 cm2/Vs at 77 K), making it a good candidate for high electron mobility transistors (HEMTs) [5]. In contrast, ZnO is a well characterized semiconductor with a room temperature direct wide bandgap of 3.3 eV, but more relevant to present optoelectronic applications is its 60 meV exciton binding energy, which will aid in the development of laser diodes [6]. ZnO also is known to be a non-toxic material which does not suffer from oxidation-induced degradation as do other semiconductors. Nanostructures of ZnO have been shown to be easily grown through almost any semiconductor growth technique. Gas sensors fabricated from multiple and single ZnO nanowires have already been reported, with future devices aimed towards transistor structures and possibly interfacing with biological cells.
A growth technique that is readily used in the growth of nanostructures is vapor liquid solid growth (VLS), first reported by Wagner et al. [
Data Loading...
