Ion induced formation of Silicon nitride substrate and GaN overlayer growth at room temperature on Si (111) surface
- PDF / 133,481 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 107 Downloads / 177 Views
1202-I05-09
Ion induced formation of Silicon nitride substrate and GaN overlayer growth at room temperature on Si (111) surface Praveen Kumar1,2, Mahesh Kumar1, Govind1, B. R. Mehta2 and S. M. Shivaprasad3* 1
Surface Physics and Nanostructure Group, National Physical Laboratory New Delhi-110012, India 2
3
Department of Physics, Indian Institute of Technology, New Delhi-110016, India
Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064, India
Abstract: GaN and related nitride semiconductors have attracted great attention in view of their wide applications in photonics and high temperature & high power electronic devices. Among other issues, reduction of defect densities by forming these interfaces at lower temperature and on novel substrates has been the motivation for several researchers. In the present study ioninduced conversion of Si (111) surface into silicon nitride at room temperature is optimized and used as substrate for the growth of Ga films. These Ga films are again nitrided by optimal N+ ion bombardment. Experiments have been performed in-situ in an ultra high vacuum chamber equipped with a Ga source and X-ray photoelectron spectrometer (XPS) at base pressure of 2x1010
torr. The energy dependence of the nitridation is carefully performed at constant flux. The
results clearly demonstrate the Si-N bond formation after a energy of 2 keV and the formation of GaN layer after 800eV of N2+ ion bombardment on Si (111) 7x7 surface and Ga adsorbed silicon nitride surface, respectively. The FWHM and chemical shifts in the core-level spectra of Si(2p), Ga(2p) and N(1s) have been analyzed to probe the interface reactions. The results demonstrate a possible novel and low temperature approach towards the integration of III-nitride & silicon technologies, since silicon nitride bonds can act as barriers to dislocation propagation. Key Words: XPS, GaN, Silicon Nitride, Si(111)
*Corresponding Author e mail: [email protected]
INTRODUCTION Group III-nitride semiconductors based on GaN have received great attention as materials for the realization of blue and green light emitting diodes [1], laser diodes [2] and hightemperature & high power devices [3]. GaN is an attractive material for short-wavelength optoelectronics and high power devices due to its unique properties, including a large direct band-gap and a high critical electrical field. However, the choice of substrate to grow epitaxial GaN is a serious issue. Recently various substrates have been tried to grow wurtzite GaN, such as sapphire [4], 6H-SiC (0001) [5], GaAs (111) [6] and Si (111) [7]. Among these substrates, silicon has become a desirable substrate material for hetero-epitaxy because of its high crystalline quality, large wafer size, low cost, and easier integration with the well-established silicon device technology. However, it is difficult to grow high quality wurtzite GaN on silicon due to the large mismatch in lattice constant (-16.9%), and thermal expansion coefficient mismatch (57%), that results in high
Data Loading...
