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对含有AlN插入层纤锌矿AlxGa1-xN/AlN/GaN异质结构,考虑有限厚势垒和导带弯曲的实际 异质结势,同时计入自发极化和压电极化效应产生的内建电场作用,采用数值自洽求解薛定谔方程和泊松方程, 获得二维电子气(2DEG)中电子的本征态和本征能级.依据介电连续模型和Loudon单轴晶体模型, 用转移矩阵法分析该体系中可能存在的光学声子模及三元混晶效应.进一步, 在室温下计及各种可能存在的光学声子散射,推广雷-丁平衡方程方法,讨论2DEG分布及二维电子迁移率的 尺寸效应和三元混晶效应.结果显示: AlN插入层厚度和AlxGa1-xN势垒层中Al组分的增加均会 增强GaN层中的内建电场强度,致使2DEG的分布更靠近异质结界面,使界面光学声子强于其他类型的 光学声子对电子的散射作用而成为影响电子迁移率的主导因素.适当调整AlN插入层的厚度和Al组分, 可获得较高的电子迁移率.
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关键词:
- AlGaN/AlN/GaN异质结构 /
- 电子迁移率 /
- 光学声子模 /
- 三元混晶效应
Adopting a numerical method of solving self-consistently the Schrdinger equation and Poisson equation through taking into account the realistic heterostructure potential, which includes the influences of energy band bending and the finite thickness of barriers, and through considering the built-in electric field induced by spontaneous and piezoelectric polarization, the eigenstates and eigenenergies of electrons in two-dimensional electron gas (2DEG) are obtained for wurtzite AlxGa1-xN/AlN/GaN heterostructures with an inserted AlN layer. Based on the continuous dielectric model and the Loudon's uniaxial crystal model, optical-phonon modes and their ternary mixed crystals effect are discussed using the transfer matrix method. Furthermore, the Lei-Ting balance equation is extended in order to investigate the distribution of 2DEG and its size effect as well as ternary mixed crystals effect on electron mobility, which under the influence of each branch of optical-phonon modes are analyzed at room temperature. The results show that the increases of the thickness of inserted AlN layer and the Al component of AlxGa1-xN in the barrier enhance the built-in electric field in the GaN layer, leading 2DEG to be much closer to the interface of a heterostructure. In addition, it can also be found that the scattering from the interface phonons is stronger than from other optical-phonons, the interface phonons play a dominant role in the total mobility. A higher electron mobility can be obtained by adjusting appropriately the thickness of inserted AlN layer and Al component.-
Keywords:
- AlGaN /AlN/GaN heterostructure /
- electron mobility /
- optical-phonon mode /
- ternary mixed crystal effect
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[57] Vurgaftman I, Meyer J R 2003 J. Appl. Phys. 94 3675
[58] [59] [60] Yu S G, Kim K W, Stroscio M A, Iafrate G J, Sun J P, Hsddad G I 1997 J. Appl. Phys. 82 3363
[61] [62] Lepkowski S P, Teisseyre H, Suski T, Perlin P, Grandjean N, Massies J 2001 Appl. Phys. Lett. 79 1483
[63] Wagner J M, Bechstedt F 2002 Phys. Rev. B 66 115202
-
[1] [2] Gaska R, Shur M S, Bykhovski A D, Orlov A O, Snider G L 1999 Appl. Phys. Lett. 74 287
[3] Smorchkova I P, Elsass C R, Ibbetson J P, Vetury R, Heying B, Fini P, Haus E, DenBaars S P, Speck J S, Mishra U K 1999 J. Appl. Phys. 86 4520
[4] [5] [6] Tao Y Q, Chen D J, Kong Y C, Shen B, Xie Z L, Han P, Zhang R, Zheng Y D 2006 J. Electron. Mater. 35 722
[7] [8] Hsu L, Walukiewicz W 1997 Phys. Rev. B 56 1520
[9] Gaska R, Yang J W, Osingsky A, Chen Q, Khan M A, Orlov A O, Snider G L, Shur M S 1998 Appl. Phys. Lett. 72 707
[10] [11] Gurusinghe M N, Davidsson S K, Andersson T G 2005 Phys. Rev. B 72 045316
[12] [13] [14] Shen L, Heikman S, Moran B, Coffie, Zhang N D, Buttari D, Smorchkova I P, Keller S, DenBaars S P, Mishra U K 2001 IEEE Electron Dev. Lett. 22 457
[15] Hsu L, Walukiewicz W 2001 J. Appl. Phys. 89 1783
[16] [17] Smorchkova I P, Chen L, Mates T, Shen L, Heikman S, Moran B, Keller S, DenBaars S P, Speck J S, Mishra U K 2001 J. Appl. Phys. 90 5196
[18] [19] [20] Miyoshi M, Ishikawa H, Egawa T, Asai K, Mouri M, Shibata T, Tanaka M, Oda O 2004 Appl. Phys. Lett. 85 1710
[21] Tlek R, Ilgaz A, Gkden S, Teke A, ztrk M K, Kasap M, z\c{celik S, Arslan E, zbay E 2009 J. Appl. Phys. 105 013707
[22] [23] Miyoshi M, Egawa T, Ishikkawa H 2005 J. Appl. Phys. 98 63713
[24] [25] Lee B C, Kim K W, Stroscio M A, Dutta M 1998 Phys. Rev. B 58 4860
[26] [27] Komirenko S M, Kim K W, Stroscio M A, Dutta M 2000 Phys. Rev. B 61 2034
[28] [29] [30] Qu Y, Ban S L 2009 Eur. Phys. J. B 69 321
[31] Qu Y, Ban S L 2010 Acta Phys. Sin. 59 4863 (in Chinese) [屈媛, 班士良 2010 59 4863]
[32] [33] Qu Y, Ban S L 2011 J. Appl. Phys. 110 013722
[34] [35] Chu R M, Zhou Y G, Zheng Y D, Han P, Shen B, Gu S L 2001 Appl. Phys. Lett. 79 2270
[36] [37] [38] Li J M, L Y W, Li D B, Han X X, Zhu Q S, Liu X L, Wang Z G 2004 J. Vac. Sci. Technol. B 22 2568
[39] L J T, Cao J C 2005 J. Appl. Phys. 97 033502
[40] [41] Hayers W, Loudon R 1964 Scattering of Light by Crystals (New York: Wiley) p169
[42] [43] [44] Yu S G, Kim K W, Bergman L, Dutta M, Stroscio M A, Zavada J M 1998 Phys. Rev. B 58 15283
[45] Holtz M, Prokofyeva T, Seon M, Copeland K, Vanbuskirk J, Williams S, Nikishin S A, Tretyakov V, Temkin H 2001 J. Appl. Phys. 89 7977
[46] [47] [48] Wang X F, da Cunha Lima I C, Lei X L 1998 Phys. Rev. B 58 12609
[49] Bungaro C, Rapcewicz K, Bernholc J 2000 Phys. Rev. B 61 6720
[50] [51] Demangeot F, Groenen J, Frandon J, Renucci M A, Briot O, Clur S, Aulombard R L 1998 Appl. Phys. Lett. 72 2674
[52] [53] [54] Wu J 2009 J. Appl. Phys. 106 011101
[55] [56] Zoroddu A, Bernardini F, Ruggerone P, Fiorentini V 2001 Phys. Rev. B 64 045208
[57] Vurgaftman I, Meyer J R 2003 J. Appl. Phys. 94 3675
[58] [59] [60] Yu S G, Kim K W, Stroscio M A, Iafrate G J, Sun J P, Hsddad G I 1997 J. Appl. Phys. 82 3363
[61] [62] Lepkowski S P, Teisseyre H, Suski T, Perlin P, Grandjean N, Massies J 2001 Appl. Phys. Lett. 79 1483
[63] Wagner J M, Bechstedt F 2002 Phys. Rev. B 66 115202
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