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A self-terminating gate recess wet etching technique with thermal oxidation of the AlGaN/GaN layer followed by etching in potassium hydroxide (KOH) solution was recently proposed by the present authors for normally-off AlGaN/GaN metal–oxide semiconductor field effect transistors (MOSFETs). In this present reported work, the oxidation process inside the AlGaN/GaN heterostructure involved in this technique was analysed using several material characterisation methods. The measurement results show that the concentration and depth of the O element distribution increase with increased thermal oxidation temperature. It is worth noting that after 650°C oxidation almost no O element could be found in the GaN layer and the O element mainly locates in the AlGaN layer with an obvious correlation between the distribution of Al and O elements, where the Al(Ga)-oxide was detected by X-ray photoelectron spectroscopy, which could be etched by 70°C KOH. Thus, self-terminating wet etching on the AlGaN/GaN material is achieved.
References
-
-
1)
-
10. Wang, X.L., Zhao, D.G., Chen, J., et al: ‘Effect of oxidation on the optical and surface properties of AlGaN’, Appl. Surf. Sci., 2006, 252, (24), pp. 8706–8709 (doi: 10.1016/j.apsusc.2005.12.057).
-
2)
-
4. Buttari, D., Chini, A., Meneghesso, G., et al: ‘Systematic characterization of Cl2 reactive ion etching for gate recessing in AlGaN/GaN HEMTs’, IEEE Electron Device Lett., 2002, 23, (3), pp. 118–120 (doi: 10.1109/55.988810).
-
3)
-
2. Wang, R., Saunier, P., Xing, X., et al: ‘Gate-recessed enhancement-mode InAlN/AlN/GaN HEMTs with 1.9 A/mm drain current density and 800 mS/mm transconductance’, IEEE Electron Device Lett., 2010, 31, (12), pp. 1383–1385 (doi: 10.1109/LED.2010.2072771).
-
4)
-
11. Higashiwaki, M., Chowdhury, S., Swenson, B.L., et al: ‘Effects of oxidation on surface chemical states and barrier height of AlGaN/GaN heterostructures’, Appl. Phys. Lett., 2010, 97, (22), pp. 222104–222104–3 (doi: 10.1063/1.3522649).
-
5)
-
13. Jeon, C.M., Lee, J.L., et al: ‘Enhancement of Schottky barrier height on AlGaN/GaN heterostructure by oxidation annealing’, Appl. Phys. Lett., 2003, 82, (24), pp. 4301–4303 (doi: 10.1063/1.1583140).
-
6)
-
5. Xu, Z., Wang, J., Liu, Y., et al: ‘Fabrication of normally off AlGaN/GaN MOSFET using a self-terminating gate-recess etching technique’, IEEE Electron Device Lett., 2013, 34, (7), pp. 855–857 (doi: 10.1109/LED.2013.2264494).
-
7)
-
2. Zhaung, D., Edgar, J.H.: ‘Wet etching of GaN, AlN, and SiC: a review’, Mater. Sci. Eng. R Rep., 2005, 48, pp. 1–46 (doi: 10.1016/j.mser.2004.11.002).
-
8)
-
7. Anderson, T.J., Tadjer, M.J., Mastro, M.A., et al: ‘An AlN/ultrathin AlGaN/GaN HEMT structure for enhancement-mode operation using selective etching’, IEEE Electron Device Lett., 2009, 30, (12), pp. 1251–1253 (doi: 10.1109/LED.2009.2033083).
-
9)
-
12. Kim, H., Schuette, M.L., Lee, J., et al: ‘Passivation of surface and interface states in AlGaN/GaN HEMT structures by annealing’, J. Electron. Mater., 2007, 36, (9), pp. 1149–1155 (doi: 10.1007/s11664-007-0189-2).
-
10)
-
3. Kim, K., Jung, S., Kim, D., et al: ‘Effects of TMAH treatment on device performance of normally off Al2O3/GaN MOSFET’, IEEE Electron Device Lett., 2011, 32, (10), pp. 1376–1378 (doi: 10.1109/LED.2011.2163293).
-
11)
-
U.K. Mishra ,
P. Parikh ,
Y.-F. Wu
.
AlGaN/GaN HEMTs—an overview of device operation and application.
Proc. IEEE
,
6 ,
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1031
-
12)
-
5. Ota, K., Endo, K., Okamoto, Y., et al: ‘A normally off GaN FET with high threshold voltage uniformity using a novel piezo neutralization technique’. IEEE IEDM, Baltimore, MD, USA, December 2009, pp. 1–4.
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