Simon Watkins' Publications

Under Review/Accepted:


S. Alagha, Sebastian Heedt, Daniel Vakulov, F. Mohammadbeigi, E. Senthil Kumar, Thomas Schaepers, Dieter Isheim, S.P. Watkins, K.L. Kavanagh, “Characterization of Ga-doped ZnO nanowires" submitted, 20 June 2017.

D.J. Dvorak, A. Darbandi, K.L. Kavanagh, S.P. Watkins, "Regrowth mechanism for oxide isolation of GaAs nanowires" accepted in Nanotechnology, July 2017.


S. Alagha, A. Shik, H. E. Ruda, I. Saveliev, K. L. Kavanagh, and S. P. Watkins, “Numerical analysis of space-charge-limited current in nanowires”, J. Appl. Phys. 121, 174301 (2017)

F. Mohammadbeigi, T. Kure, G. Callsen, E. Senthil Kumar, M.R. Wagner, A. Hoffmann, and S.P. Watkins, "Influence of carbon doping and hydrogen co-doping on acceptor related optical transitions in ZnO nanowires", Semicond. Sci. Technol. 32  045017 (2017)

Todd Karin, Xiayu Linpeng, M.V. Durnev, Russell Barbour, M.M. Glazov, E.Ya. Sherman, Colin Stanley, S.P. Watkins, Satoru Seto, and Kai-Mei C. Fu, “Longitudinal spin-relaxation of donor-bound electrons in direct bandgap semiconductors”, Phys. Rev. B94, 125401 (2016).

Ali Darbandi and S.P. Watkins, "Measurement of minority carrier diffusion lengths in GaAs nanowires by a nanoprobe technique", J. Appl. Phys. 120, 014301(2016)

Ali Darbandi, James McNeil, Azadeh Akhtari-Zavareh, S.P.Watkins, and Karen L. Kavanagh, “Direct Measurement of the Electrical Abruptness of a Nanowire p-n Junction”, Nano Letters, 2 June 2016.

Mingze Yang, Ali Darbandi, S.P. Watkins, and Karen Kavanagh, “Epitaxial Fe on Free-standing GaAs Nanowires”, Semiconductor Science and Technology, 31, 074003 (2016).

E. Senthil Kumar, F. Mohammadbeigi, L. A. Boatner, and S. P. Watkins, "High-resolution photoluminescence spectroscopy of Sn-doped ZnO single crystals", J. Luminescence, 176,47 (2016).

A. Darbandi, K. L. Kavanagh, and S. P. Watkins, “Lithography-free fabrication of core-shell GaAs nanowire tunnel diodes”, Nano Lett.14, 5408 (2015)

F. Mohammadbeigi, E. Senthil Kumar, S. AlaghaI. Anderson and S. P. Watkins, "Carbon related donor bound exciton transitions in ZnO nanowires" J. Appl. Phys. 116, 053516 (2014)

A. Darbandi, O. Salehzadeh, P. Kuyanov, R. R. LaPierre, and S. P. Watkins, "Surface passivation of tellurium-doped GaAs nanowires by GaP: effect on electrical conduction", J. Appl. Phys. 115, 234305 (2014)

O. Salehzadeh, B. Cawston-Grant, S.P. Watkins, and P.M. Mooney, "Electrical Characterization of In-Place Bonded Interfaces", Semicond. Sci. Technol. 29 085002 (2014).

P.M. Mooney, K.L. Kavanagh, D. OwenD. LacknerB. Cawston-GrantA.F. BasileO. Salehzadeh, and S.P. Watkins, "Characterization of solution-bonded GaAs/InGaAs/GaAs features on GaAs", Semicond. Sci. Technol. 29, 075009 (2014).

O. Salehzadeh, K. L. Kavanagh, and S. P. Watkins, Geometric limits of coherent III-V core/shell nanowires, J. Appl. Phys. 114, 054301 (2013)

O. Salehzadeh, K. L. Kavanagh, and S. P. Watkins, "Growth and strain relaxation of GaAs and GaP  nanowires with GaSb shells", J. Applied Phys., 113, 134309 (2013).

E. Senthil Kumar, F. Mohhamadbegi, D. Zeng, I. Anderson, T. Wintchel, and S. P. Watkins, "Optical evidence for donor behavior of Sb in ZnO nanowires", Appl. Phys. Lett. 102, 132105 (2013).

O. Salehzadeh, K. L. Kavanagh, and S. P. Watkins, "Growth and strain relaxation of GaAs (GaP)/GaSb core/shell nanowires", accepted in J. Applied Phys., Feb. 2013.

E. Senthil Kumar, I. Anderson, Z. Deng, F. Mohammadbeigi, T. Wintschel, D. Huang, S.P. Watkins, “Effect of group-III donors on high resolution photoluminescence and microstructure of ZnO nanowires grown by metalorganic chemical vapor deposition”, Semicond. Sci. Tech., 28, 045014 (2013).

S. Zhao, O. Salehzadeh, S. Alagha, K.L. Kavanagh, S.P. Watkins, and Z. Mi, "Probing the electrical transport properties of intrinsic InN nanowires", Appl. Phys. Lett. 102, 073102 (2013). 

O. Salehzadeh, X. Zhang, B.D. Gates, K.L.  Kavanagh, S.P. Watkins, “p-type doping of GaAs nanowires using carbon”, J. Appl. Physics,  112, 094323 (2012)

O. Salehzadeh, K.L. Kavanagh, and S.P Watkins, “Controlled axial and radial Te-doping of GaAs nanowires”,  J. Appl. Phys. 112, 054324 (2012)

C. Liu, O. Salehzadeh, P. J. Poole, S. P. Watkins, and K. L. Kavanagh, “Insights into semiconductor nanowire conductivity using electrodeposition”, Semiconductor Science and Technology 27, 105020 (2012).

B. Kardasz, S. P. Watkins, E.A. Montoya, C.Burrowes, E. Girt, and B. Heinrich, “Interface magnetism of iron grown on sulfur and hydrogen passivated GaAs(001)”, J. Appl. Phys., 111, 07C115 (2012)

D. Lackner, M. Steger, M.L.W. Thewalt, O. J. Pitts, Y.T. Cherng, and S.P. Watkins, E. Plis, and S Krishna, “InAs/InAsSb strain balanced superlattices for optical detectors: materials properties and energy band simulations”, J. Appl. Phys. 111, 034507 (2012)

O. Salehzadeh, M. X. Chen, K. L. Kavanagh, S. P. Watkins, “Rectifying characteristics of Te-doped GaAs nanowires”, Appl. Phys. Lett. 99, 182102, (2011)

S.P. Watkins, Z.W. Deng, D.C. Li, He. Huang, "High resolution photoluminescence spectroscopy of donors in undoped and In-doped ZnO grown by metalorganic vapor phase epitaxy", J. Appl. Phys. 110, 083506 (2011)

O. Salehzadeh, S.P. Watkins, "Control of GaAs nanowire morphology by group III precursor chemistry", J. Cryst. Growth, 325, 5,  (2011).

O. Salehzadeh, S.P. Watkins, “Effect of carbon dopant on the morphology of GaAs nanowires”, Nanotechnology 22, 165603 (2011).

D. Lackner, M. Martine, Y. T. Cherng, M. Steger, W. Walukiewicz, M. L. W. Thewalt, P. M. Mooney, and S. P. Watkins, “Electrical and optical characterization of n-InAsSb/n-GaSb heterojunctions”, J. Appl. Phys., 107, 014512 (2010) .

He Huang, Z.W. Deng, D.C. Li, E. Barbir, W.Y. Jiang, M.X. Chen, K.L. Kavanagh, P.M. Mooney, S.P Watkins, "Effect of Annealing on Structural and Optical Properties of Heavily Carbon-Doped ZnO", Semicond. Sci. Technol. 25 (2010) 045023.

W.Y. Jiang, K.L. Kavanagh, S.P. Watkins, “Growth mechanisms for atomic ordering in GaAsSb grown by MOVPE” J. Cryst. Growth, 311, 4391 (2009)

D. Lackner, O.J. Pitts, M. Steger, A. Yang, M.L.W. Thewalt, S.P. Watkins, “Strain balanced InAsSb/InAs superlattice structures with optical emission to 10 microns” Appl. Phys. Lett. 95, 081906 (2009)

D. Lackner, O. J. Pitts, S. Najmi, P. Sandhu, K. L. Kavanagh, A. Yang, M. Steger, M. L. W. Thewalt, Y. Wang, D. W. McComb, C. R. Bolognesi, S. P. Watkins, “InAsSb/InAs MQWs grown by MOCVD on GaSb for mid-IR photodetector applications”, J. Cryst. Growth,  311,  3563 (2009)

R.A. Rosenberg, M. Abu Haija, and S.P. Watkins, “X-ray and electron induced infrared emission spectroscopy”, Rev. Sci. Instruments. 80, 046104 (2009)

D.L. Owen, D. Lackner, O.J. Pitts, S.P. Watkins and P.M. Mooney, “In Place Bonding of GaAs/InGaAs/GaAs Heterostructures to GaAs(001)”, Semicond. Sci. Technol. 24, 035011 (2009)

O.J. Pitts, D. Lackner, Y.T. Cherng, S.P. Watkins, “Growth of InAsSb/InPSb heterojunctions for mid-IR detector applications”, J. Cryst. Growth, 310 4858 (2008).

D. Huang, W.Y. Jiang, S.P. Watkins, “Flow modulation epitaxy of ZnO films on sapphire substrates”, J. Cryst. Growth 310,  4050 (2008)

S. Najmi, X.K. Chen, S.P. Watkins, “Dicarbon defects in as-grown and annealed carbon doped InAs”, J. Appl. Phys. 102, 083528 (2007)

A.J. Clayton, A.A. Khandekar, T.F. Kuech, N.J. Mason, M.F. Robinson, S.P. Watkins, Y. Guo, “Growth of AlN by vectored flow epitaxy”, J. Cryst. Growth, 298, 328 (2007).

K. Alberi, J. Wu, W. Walukiewicz, K.M. Yu, O.D. Dubon, S.P. Watkins , C.X. Wang,  X. Liu, Y.-J. Cho, and J. Furdyna, “Valence band anticrossing in mismatched III-V semiconductor alloys”, Phys. Rev. B75, 045203 (2007).

K. Alberi, J. Wu, W. Walukiewicz, K. M. Yu, O. D. Dubon, S. P. Watkins, C. X. Wang, X. Liu, Y.-J. Cho, and J. K. Furdyna, “Valence band anticrossing in mismatched III-V semiconductor alloys”,  Phys. Stat. Sol. (c) 4,1711 (2007)

H. G. Liu, D.W. DiSanto, S. P. Watkins, and C. R. Bolognesi, “InP/GaAsSb/InP DHBTs with fT = 300 GHz and high maximum oscillation frequencies: the effect of scaling on device performance”, Phys. Stat. Sol.(c) 3, 4612 (2006)

Y. Guo, O. J. Pitts, W.Jiang, S.P. Watkins, “Numerical Optimization of an Optical Showerhead Reactor Design for Organometallic Vapor Phase Epitaxy” J. Cryst. Growth, 297, 345 (2006)

S. Najmi, M.X. Chen, A. Yang, M. Steger, M.L.W. Thewalt, S.P. Watkins, “Local Vibrational Mode Study of Carbon Doped InAs”, Phys. Rev. B 74, 113202 (2006).

H.G. Liu, S.P. Watkins, and C.R. Bolognesi, “15-nm base type-II InP/GaAsSb/InP DHBTs with Ft=384GHz and a 6-V BVCEO”, IEEE Transactions on Electron Devices, 53, 559 (2006).

S. Najmi, X. Zhang, X.K. Chen, M. L. W. Thewalt, S.P. Watkins, “Raman scattering in carbon-doped InAs”, Appl. Phys. Lett. 88, 041908 (2006).

W.Y. Jiang, J.Q. Liu, X. Zhang, M.L.W. Thewalt, K.L. Kavanagh, S.P. Watkins, “Microstructure of ordered nanodomains induced by Bi surfactant in OMVPE-grown GaAsSb” J. Cryst. Growth, 287, 541 (2006).

T.S. Rao, M.G. So, W.Jiang, T.Mayer, S. Roorda, S.C. Gujrathi, M.L.W.Thewalt, C.R. Bolognesi, and S.P. Watkins, “Optical and electrical characterization of OMVPE-grown AlGaAsSb  epitaxial layers on InP substrates”, J. Cryst. Growth, 287, 532, (2006)

C.R. Bolognesi, H.G. Liu, N. Tao, X. Zhang, S. Bagheri-Najmi, and S.P. Watkins, “Neutral base recombination in InP/GaAsSb/InP double-heterostructure bipolar transistors: Suppression of Auger recombination in p+ GaAsSb base layers”, Appl. Phys. Lett. 86, 253506 (2005).

W.Y. Jiang, J.Q. Liu, M.G. So, K. Myrtle, K.L. Kavanagh, S.P. Watkins, “Surface modifications induced by bismuth on (001) GaAs surfaces” J. Cryst. Growth, 277, 85, (2005)

L. Zheng, Z. Zhang, Y. Zeng, S.R. Tatavarti, S.P. Watkins, C.R. Bolognesi, S. Demiguel, J.C. Campbell, “Demonstration of high-speed staggered lineup GaAsSb/InP Uni-traveling carrier photodiodes”, IEEE Photonics Technology Letters, 17, 651, (2005).

H. G. Liu, N. Tao, S. P. Watkins, and C. R. Bolognesi, “Extraction of the Average Collector Velocity in High-Speed “Type-II” InP–GaAsSb–InP DHBTs”, IEEE Electron Dev. Lett. 25, 769 (2004)

W. Jiang, J. Q. Liu, M.G. So, T. S. Rao, K.L. Kavanagh, and S.P. Watkins, “Effect of Bi surfactant on atomic ordering of GaAsSb”, Appl. Phys. Lett., 85, 5589 (2004).

Z.Q. Li, V. Zhou, S. Li, T.S. Rao, W.Y. Jiang, S.P. Watkins, “Chemical kinetics and design of gas inlets for III-V growth by MOVPE in a quartz showerhead reactor” accepted in J. Cryst. Growth, 272, 47 (2004).

O.J. Pitts, S.P. Watkins, C. X. Wang, J. A. H. Stotz, T. A. Meyer, M. L. W. Thewalt “Ultrathin type-II GaSb/GaAs quantum wells grown by OMVPE”, J. Cryst. Growth, 269, 187, (2004).

S. Lam, C.R. Bolognesi, and S.P. Watkins, "Characterization of InP electron-initiated impact ionization in low electric fields using abrupt junction NpN InP/GaAsSb/InP double heterojuntion bipolar transistors", Appl. Phys. Lett., 83, 5548 (2003).

C.R. Bolognesi, M.W. Dvorak, S.P. Watkins, “Type II Base-Collector Performance Advantages and Limitations in High-Speed NPN double heterojunction bipolar transistors (DHBTs)” IEICE Trans. Electron. E85-C, 1929 (2003)

O.J. Pitts, S.P. Watkins, C.X. Wang, V. Fink, and K.L. Kavanagh, "Antimony segregation in GaAs-based multiple quantum well structures" J. Cryst. Growth, 254, 28, (2003)

R.D. Wiersma, J.A.H. Stotz, O.J. Pitts, C.X. Wang, M.L.W. Thewalt, and S.P. Watkins, "Electrical and optical properties of carbon doped GaSb", Phys. Rev. B67, 165202 (2003)

S.P. Watkins, R.D.Wiersma, C.X. Wang, O.J. Pitts, and C.R. Bolognesi, "Structural effects of carbon in GaSb grown by metalorganic vapor phase epitaxy", J. Cryst. Growth, 248, 274 (2003).

C.X. Wang, O.J. Pitts, and S.P. Watkins, "Time-resolved reflectance difference spectroscopy study of Sb- and As- terminated InP(100) surfaces", J. Cryst. Growth, 248, 259 (2003).

O.J. Pitts, S.P. Watkins, and C.X. Wang, "RDS characterization of GaAsSb and GaSb grown by MOVPE", J. Cryst. Growth, 248, 249 (2003).

X.K. Chen, R. Wiersma, C.X. Wang, O.J. Pitts, C. Dale, C.R. Bolognesi, S.P. Watkins, "Local vibrational modes of carbon in GaSb and GaAsSb", Appl. Phys. Lett. 80, 1942 (2002).

C.R. Bolognesi, M.W. Dvorak, N. Matine, O.J. Pitts, S.P. Watkins, "Ultrahigh performance staggered lineup ("Type-II") InP/GaAsSb/InP NpN double heterojunction bipolar transistors", Jpn. J. Appl. Phys. 41,1131 (2002).

C.R. Bolognesi, N.Matine, M.W. Dvorak, P. Yeo, X.G. Xu, and S.P Watkins, "InP/GaAsSb/InP double HBTs: a new alternative for InP-based DHBTs", IEEE Trans. Electron Dev., 48, 2631 (2001).

R. Wiersma, J.A.H. Stotz, O.J. Pitts, C.X. Wang, M.L.W. Thewalt, and S.P. Watkins, "P-type  carbon doping of GaSb", J. Electron. Materials, 30, 1429 (2001).

O.J. Pitts, S.P. Watkins, C.X. Wang, J.A.H. Stotz, and M.L.W. Thewalt, "in situ monitoring, structural and optical properties of ultrathin GaSb/GaAs quantum wells, grown by OMVPE", J. Electron. Materials, 30, 1412 (2001).

V. Fink, E. Chevalier, O.J. Pitts, M.W. Dvorak, K.L. Kavanagh, C.R. Bolognesi, S.P. Watkins, S. Hummel, N. Moll, "Anisotropic resistivity  correlated with atomic ordering in p-type GaAsSb", Appl. Phys. Lett., 79, 2384 (2001).

M.W. Dvorak, C.R. Bolognesi, O.J. Pitts, S.P. Watkins, "300 GHz InP/GaAsSb/InP double HBTs with high current capability and BVCEO ³6V", IEEE Electron Device Lett., 22, 361 (2001).

M. W. Dvorak, N. Matine, C. R. Bolognesi, X. G. Xu and S. P. Watkins, "Design and performance of InP/GaAsSb/InP double heterojunction bipolar transistors", J. Vac. Sci. Technol. A 18, 761 (2000).

S.P. Watkins, T. Pinnington, J. Hu, P. Yeo, M. Kluth. N.J. Mason, R.J. Nicholas and P.J. Walker, "Infrared single wavelength gas composition monitoring for metalorganic vapour phase epitaxy",  J. Cryst. Growth, 221, 166 (2000).

S.P. Watkins, O. Pitts, C. Dale, X.G.Xu,  M. Dvorak, N. Matine, and C.R. Bolognesi, "Heavily carbon-doped GaAsSb grown on InP for HBT applications", J. Cryst. Growth,  221, 59 (2000).

 R. Beaudry, X.G. Xu, and S.P. Watkins, "Photoreflectance study of phosphorous passivation of GaAs" J. Appl. Phys. 87, 7838 (2000).

 C. R. Bolognesi and S. P. Watkins, "InP-Based Double Heterojunction Bipolar Transistors: It May Not Have to be GaInAs", Compound Semiconductor 6, 94 (2000).

 J.A. Gupta, S.P. Watkins, E.D. Crozier, J.C. Woicik, D.A. Harrison, D. Jiang, I.J. Pickering, and B.A Karlin, "Layer perfection in ultrathin InAs quantum wells in GaAs (001)", Phys. Rev. B61, 2073(2000).