Effect of porosity on GaN for hydrogen gas sensing
Keywords:Porous GaN, Pd Schottky contact, Gas Sensing, Electroless Chemical Etching,
AbstractPorous wide bandgap semiconductors have been widely studied in the last decade due to their unique properties compared to the bulk crystals. The high surface area, shift of bandgap, luminescence intensity enhancement and efficient photoresponse when porosity is formed can be tailored to fabricate new sensing devices. In this work, porous GaN was prepared by ultraviolet (UV) assisted electroless chemical etching method. The commercial Si doped n-type GaN film grown on two inches diameter sapphire (0001) substrate with GaN thickness of 5.5 μm was used in this study. The wafer was then cleaved into few pieces, and these samples were etched in HF:H2O2:CH3OH under UV illumination for 60 minutes. The structural properties was characterized using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Hydrogen sensor was subsequently fabricated by depositing Pt Schottky contact onto the porous GaN sample. The effect of sensing dilute H2 gas with different concentration which is 1% and 2% H2 in a N2 gas ambient was analyzed. The Schottky barrier height of the gas sensor samples was reduced upon exposure to gas. The porous GaN resulted better sensitivity compared to the as grown GaN sample in H2 gas sensing
H. Hasagawa and T. Sato, Electrochimica Acta, 50 (2005), 3015-3027.
X. Li, Y. W. Kim, P. W. Bohn and I. Adesida, Appl. Phys. Lett, 80 (2002), 980.
A. Lloyd- Spetz, A , Baranzahi, P. Tobias, I. Lundstrom, Phys. Stat. Sol, (a) 162 (1997), 493.
M. S. Shur, A. D. Bykhovski, R. Gasak, M. A. Khan, MIJ- NSR, 4 (1999).
Y. Alifragis, G. Konstantinidis, A. Georgakilas, N. Chaniotakis, Electroanalysis, 17 (2005), 527.
J. Schwalwig, G. Muller, U. Karrer, M. Eichkoff, O. Ambacher, M. Stutzmann, L. Gorgens, G. Dollinger, Appl. Phys. Lett, 80 (2002) 1222
J. A. Manthey, K. Grohman, and N. Guthrie, Curr. Med. Chem., 8 (2001), 135-153.
M. Ali, V. Cimalla, V. Lebedev, H. Romanus, V. Tilak, D. Merfeld, P. Sandvik, O. Ambacher, Science Direct, 113 (2006), 797-804.
C. F. Coombs, Electronic Instruments Handbook (1999).
B. P Luther, S. D. Wolter and S. E. Mohney, Sensors and Actuator, B56 (1999), 164-168
D. Zhuang and J. H. Edgar. Material Science ad Engineering:R:Reports V8, 1 (2005), 1-46.  J. Song and W. Lu, Solid State Electronics, 49 (2005), 1330 – 1334.
J. Diaz, L. T. Williamson, X. Guo, A. Sood and W. P. Bohn, NRC – CSTI, 514 (2006), 120 - 126.
J. Wang, D. G Zhao, Y. P. Sun, L. H. Duan, Y. T Wang, S. M Zhang, H Yang, Shengqiang Zhou, M. Wu, J. Phys. D: Phys, 36 (2003), 1018 - 1022
D. S. Lee, J. H. Lee, Y. H. Lee, D. D. Lee, Sensors and Actuators, B6989 (2003), 1 6.
J. Kim, B. P. Gila, G. Y. Chung, C. R. Abernathy, S. J. Pearton, F. Ren, Solid States Electronics, 47 (2003), 1069-1073
J. Schalwig, G. Muller, M. Eichkoff, O. Ambacher, M. Stutzmann, Mat. Science. Engineering, 93 (2002), 207-214
L. Wang, M. I. Nathan, T. H. Lim, M. A. Khan, Q. Chen, Appl. Phys. Lett, 68 (1996), 1267
M. Ali, V. Cimalia, V. Lebedev, H. Romanus, V. Tilak, D. Merfeld, P. Sandvik, O. Ambacher, Sensors and Actuators, B113 (2006) 797-804.