[1] Campbell J C and Madhukar A 2007 Proc. IEEE
95 1815

[2] Zhao Z Y, Yi C, Stiff-Roberts A D, Hoffman A J, Wasserman
D and Gmachl C 2007 Infrared Phys. Technol. 51 131

[3] Krishna S, Gunapala S D, Bandara S V, Hill C and Ting D Z
2007 Proc. IEEE 95 1838

[4] Amtout A, Raghavan A, Rotella P, Winckel G V, Stintz A and
Krihna S 2004 J. Appl. Phys. 96 3782

[5] Li S S and Xia J B 1997 Phys. Rev. B 55 15434

[6] Li S S, Xia J B, Yuan Z L and Xu Z Y 1996 Phys. Rev.
B 54 11575

[7] Han X X, Li J M, Wu J J, Cong G G, Liu X L, Zhu Q S and
Wang Z G 2005 Phys. Rev. B 98 053703

[8] Krishna S 2005 Infrared Phys. Technol. 47 153

[9] Krishna S Proceedings of 2005 Fifth IEEE Conference
on Nanotechnology (Nagoya, Japan, 1-15 July 2005)

[10] Ariyawansa G, UnilPerera A G , Raghavan G S, Winckel G V,
Stintz A and Krishna S 2005 IEEE Photon. Technol. Lett.
17 1064

[11] Krishna S, Forman D, Annamalai S and Dowd P 2005
Appl. Phys. Lett. 86 193501

[12] Vukmirovi\'c N, Indjin D, Ikoni? Z and Harrison P 2006
Appl. Phys. Lett. 88 251107

[13] Nam H D, Doyennette L, Song J D, Choi W J, Yang H S, Lee
J I and Julien F H 2006 Physica E 32 524

[14] Lv W, Li D B, Zhang Z Y, Li C R, Zhang Z, Xu B and Wang Z
G 2005 Chin. Phys. Lett. 22 967

[15] Wang Z C, Chen Y H, Xu B, Liu F Q, Shi L W, Tang C G and
Wang Z G 2008 Physica E 40 633

[16] Krishna S, Raghavan S, Winckel G and Stintz A 2003
Appl. Phys. Lett. 83 2745

[17] Lim H 2005 Phys. Rev. B 72 085332

[18] Jang X D, Li S S and Tidrow M Z 1999 Physica E
5 27