Growth of GaN on (100)Si Using a New C-H and N-H Free Single-Source Precursor
- PDF / 1,491,364 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 86 Downloads / 136 Views
ABSTRACT We have demonstrated growth of crystalline GaN on Si substrates by using, for the first time, a novel inorganic precursor C12 GaN 3 and ultra-high-vacuum chemical vapor deposition techniques. Cross-sectional electron microscopy of the highly conformal films showed columnar growth of wurtzite GaN while Auger and RBS oxygen- and carbon-resonance spectroscopies showed that the films were pure and highly homogeneous. In addition to the high growth rates of 70-500 Ak per minute, the low deposition temperature of 550-700 °C, and the nearly perfect GaN stoichiometry that we obtain, another notable advantage of our method is that it provides a carbon-free growth environment which is compatible with p-doping processes.
INTRODUCTION The potential of the group III nitrides, InN, GaN, and AIN, for microelectronic and optoelectronic applications is well recognized [1]. In principle, bandgap variation ranging from 1.8 eV (INN) to 6.3 eV A1N can be achieved by suitable alloy combinations. The use of GaN in the fabrication of light emitting diodes has been demonstrated [2], but fabrication of blue-laser diodes and other high-power, high-frequency and high-temperature GaN-based devices has not yet been realized. A major reason is that the growth of good quality epitaxial nitride films is hindered by the lack of suitable substrate material, and achieving p-type doping is another serious difficulty. A further problem is the high background of n-type carrier concentration caused primarily by nitrogen deficiencies. Much attention has recently been given to the nature of the structural defects present in wurtzite GaN films grown by CVD [3] and molecular beam epitaxy [4] methods, and it is clear that such factors as the substrate orientation and the nature of any buffer layers have a major influence on the thin-film microstructure. Moreover, it has recently been concluded that a high density of threading defects originating at the substrate-film interface must be considered as inevitable whenever materials that are nonisomorphic with GaN are used as the substrate [5]. Consequently, not only is there a pressing need to develop GaN films of better quality but alternative substrates also need to be investigated. We are exploring new ways to grow nitride films using novel synthetic approaches. Our primary aim is to utilize simple inorganic precursors that would allow us to grow stoichiometric materials (no nitrogen vacancies), in a carbon-free environment which should not interfere with p-doping processes. The ultimate objective is to grow defect-free layers on suitable substrate materials that would promote crystalline perfection. In this report we describe our first synthetic approach which primarily involves surface decomposition of a unimolecular precursor, C12GaN3, with a "preformed" strong GaN bond, at very low pressures in a custom-built UHV-CVD system. 79 Mat, Res. Soc. Symp. Proc. Vol. 395 ©1996 Materials Research Society
We have prepared this single source inorganic precursor which is free of C and H via single-step syn
Data Loading...
