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The excessive leakage current, commonly observed in GaN Schottky barrier diodes (SBDs), severely degrades device electrical performance and long-term reliability. This leakage current relates to the dislocation-related conductive states as observed by microscopy. Up to now, various transport models have been proposed to explain the leakage current, but none of them can clearly describe in physics the electrically active dislocations. One just equivalently regarded the electric defect as a continuum conductive defect state within the forbidden band, without considering the microscopic electrical properties of the dislocations. Here in this work, on the basis of numerical simulation, we propose a phenomenological model for the electrically active dislocations to explain the leakage conduction of the GaN Schottky diodes, which are fabricated on a freestanding bulk substrate n-GaN wafer with a low dislocation density of about 1.3106 cm-2. In this model, we emphasize that the acceptor-like traps at the core of dislocations could capture electrons from the nearby donor-like traps, resulting in a high Coulomb potential and a decreasing potential at the donor-like sites. In this case, the core of dislocations would be negatively charged, and not favor the electron transport due to a strong Coulomb scattering effect, while the shallow donor-like traps around them can lead to a significant tunneling leakage component. This model is consistent well with the common observation of the localized currents at the edges of the surface V-defects in GaN. The shallow donor-like defects in GaN induced by the substitution of oxygen for nitrogen (ON), rather than the nitrogen vacancies, act as the dominant donor impurities responsible for the significant leakage current, which has a density on the order of 1018 cm-3 and an activation energy of about 47.5 meV, because 1) it has been demonstrated that during the material growth, oxygen diffusion toward the surface pits of dislocations via nitrogen vacancies could produce an exponentially decayed distribution with a density of at least 1017 cm-3, in good agreement with our derivation; 2) by the first principle calculation, the thermal activation energy of the oxygen-related donors is determined to be about 50 meV, which is very close to our derived 47.5 meV. According to this model, we propose that reducing the ON defect density during device growth is a feasible method to suppress the high leakage current in GaN-based SBDs. In addition, this study can also improve our understanding of the leakage current in other GaN-based devices.
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Keywords:
- conductive dislocation /
- GaN Schottky diode /
- shallow donor state /
- leakage current
[1] Cao X A, Stokes E B, Sandvik P M, LeBoeuf S F, Kretchmer J, Walker D 2002 IEEE Electron. Dev. Lett. 23 535
[2] Hsu J W P, Manfra M J, Molnar R J, Heying B, Speck J S 2002 Appl. Phys. Lett. 81 79
[3] Miller E J, Yu E T, Waltereit P, Speck J S 2004 Appl. Phys. Lett. 84 535
[4] Miller E J, Schaadt D M, Yu E T, Poblenz C, Elsass C, Speck J S 2002 J. Appl. Phys. 91 9821
[5] Zhang H, Miller E J, Yu E T 2006 Appl. Phys. Lett. 99 023703
[6] Lei Y, Lu H, Cao D S, Chen D J, Zhang R, Zheng Y D 2013 Solid State Electron. 82 63
[7] Hashizume T, Kotani J, Hasegawa H 2004 Appl. Phys. Lett. 84 4884
[8] Ren B, Liao M, Sumiya M, Wang L, Koide Y, Sang L 2017 Appl. Phys. Express 10 051001
[9] Sze S M, Ng K K 1981 Physics of Semiconductor Devices p163 (New York:Wiley)
[10] Look D C, Stutz C E, Molnar R J, Saarinen K, Liliental-Weber Z 2001 Solid State Commun. 117 571
[11] Ren J, Yan D W, Yang G F, Wang F X, Xiao S Q, Gu X F 2015 J. Appl. Phys. 117 154503
[12] Ren J, Mou W J, Zhao L N, Yan D W, Yu Z G, Yang G F, Xiao S Q, Gu X F 2017 IEEE Trans. Electron Devices 64 407
[13] Hawkridge M E, Cherns D 2005 Appl. Phys. Lett. 87 221903
[14] Roy T, Zhang E X, Puzyrev Y S, Shen X, Fleetwood D M, Schrimpf R D, Koblmueller G, Chu R, Poblenz C, Fichtenbaum N, Suh C S, Mishra U K, Speck J S, Pantelides S T 2011 Appl. Phys. Lett. 99 203501
[15] Jiang R, Shen X, Chen J, Duan G X, Zhang E X, Fleetwood D M, Schrimpf R D, Kaun S W, Kyle E C H, Speck J S, Pantelides S T 2016 Appl. Phys. Lett. 109 023511
[16] Elsner J, Jones R, Heggie M I, Sitch P K, Haugk M, Frauenheim T, berg S, Briddon P R 1998 Phys. Rev. B 58 12571
[17] Oila J, Kivioja J, Ranki V, Saarinen K, Look D C, Molnar R J, Park S S, Lee S K, Han J Y 2003 Appl. Phys. Lett. 82 3433
[18] Lei H, Leipner H S, Schreiber J, Weyher J L, Wosiński T, Grzegory I 2002 J. Appl. Phys. 92 6666
[19] Cherns D, Jiao C G 2001 Phys. Rev. Lett. 87 205504
[20] Cao X A, Teetsov J A, Shahedipour-Sandvik F, Arthur S D 2004 J. Cryst. Growth 264 172
[21] Han S W, Yang S, Sheng K 2018 IEEE Electron. Dev. Lett. 39 572
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[1] Cao X A, Stokes E B, Sandvik P M, LeBoeuf S F, Kretchmer J, Walker D 2002 IEEE Electron. Dev. Lett. 23 535
[2] Hsu J W P, Manfra M J, Molnar R J, Heying B, Speck J S 2002 Appl. Phys. Lett. 81 79
[3] Miller E J, Yu E T, Waltereit P, Speck J S 2004 Appl. Phys. Lett. 84 535
[4] Miller E J, Schaadt D M, Yu E T, Poblenz C, Elsass C, Speck J S 2002 J. Appl. Phys. 91 9821
[5] Zhang H, Miller E J, Yu E T 2006 Appl. Phys. Lett. 99 023703
[6] Lei Y, Lu H, Cao D S, Chen D J, Zhang R, Zheng Y D 2013 Solid State Electron. 82 63
[7] Hashizume T, Kotani J, Hasegawa H 2004 Appl. Phys. Lett. 84 4884
[8] Ren B, Liao M, Sumiya M, Wang L, Koide Y, Sang L 2017 Appl. Phys. Express 10 051001
[9] Sze S M, Ng K K 1981 Physics of Semiconductor Devices p163 (New York:Wiley)
[10] Look D C, Stutz C E, Molnar R J, Saarinen K, Liliental-Weber Z 2001 Solid State Commun. 117 571
[11] Ren J, Yan D W, Yang G F, Wang F X, Xiao S Q, Gu X F 2015 J. Appl. Phys. 117 154503
[12] Ren J, Mou W J, Zhao L N, Yan D W, Yu Z G, Yang G F, Xiao S Q, Gu X F 2017 IEEE Trans. Electron Devices 64 407
[13] Hawkridge M E, Cherns D 2005 Appl. Phys. Lett. 87 221903
[14] Roy T, Zhang E X, Puzyrev Y S, Shen X, Fleetwood D M, Schrimpf R D, Koblmueller G, Chu R, Poblenz C, Fichtenbaum N, Suh C S, Mishra U K, Speck J S, Pantelides S T 2011 Appl. Phys. Lett. 99 203501
[15] Jiang R, Shen X, Chen J, Duan G X, Zhang E X, Fleetwood D M, Schrimpf R D, Kaun S W, Kyle E C H, Speck J S, Pantelides S T 2016 Appl. Phys. Lett. 109 023511
[16] Elsner J, Jones R, Heggie M I, Sitch P K, Haugk M, Frauenheim T, berg S, Briddon P R 1998 Phys. Rev. B 58 12571
[17] Oila J, Kivioja J, Ranki V, Saarinen K, Look D C, Molnar R J, Park S S, Lee S K, Han J Y 2003 Appl. Phys. Lett. 82 3433
[18] Lei H, Leipner H S, Schreiber J, Weyher J L, Wosiński T, Grzegory I 2002 J. Appl. Phys. 92 6666
[19] Cherns D, Jiao C G 2001 Phys. Rev. Lett. 87 205504
[20] Cao X A, Teetsov J A, Shahedipour-Sandvik F, Arthur S D 2004 J. Cryst. Growth 264 172
[21] Han S W, Yang S, Sheng K 2018 IEEE Electron. Dev. Lett. 39 572
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