Texas State University Logo
Banner Image
MSEC
601 University Drive
San Marcos, TX 78666
Office (512) 245-1839
Fax (512) 245-3675

Online Resources

Helpful Links

Join the Conversation

adjust type sizemake font smallermake font largerreset font size

Mark Holtz, Ph.D.

Holtz

University Chair

Materials Science, Engineering, and Commercialization

Department of Physics


Ph.D. Physics, Viginia Tech, Blacksburg Virginia (1987)

BS Physics, Bradley University, Peoria, Illinois (1980)

 

 

 

Optical Properties of Semiconductors—

Fundamental Physics to Applied Materials Research

Welcome to the Holtz Laboratory website! Our optics research group at Texas State University focuses on understanding fundamental and applied properties of semiconductors. Of particular interest are the III-nitrides, which have applications including high-power transistors, light-emitting and laser diodes, and photovoltaics. We study the underlying physics related to optical and vibrational properties of nitride semiconductors, which are the foundation of these applications. We use our optics knowledge to carry out applied materials research for device design and processing issues, such as abating self-heating in high-power electronics and photonics.

If you enjoy fundamental physics and hands-on experimental science, and care about the practical application of your work, this research is for you!

Biosketch: (Google Scholar web page)

Mark Holtz is an experimental physicist working in nanoscale materials, particularly on questions relating to group III-nitride semiconductors, device design and processing, device self-heating, and thermal properties. He has been involved in condensed matter physics research since 1984. Prior to arriving at Texas State University in 2013, Dr. Holtz was Professor of Physics at Texas Tech University (1991-2013).

Dr. Holtz has published over 125 peer-reviewed journal articles along with numerous conference proceedings. He has received over $4.5M in external funding on grants and contracts totaling in excess of $15.8M from federal, state, and private agencies. He has advised and co-advised ten PhD students, over 50 MS students, and postdoctoral researchers, all of whom are working in industry or academia. 

Other Affiliations:

Texas Tech University (1991-2013 professor)

Max Planck Institut FKF (1987-1989 postdoc)

Michigan State University (1989-1991 visiting scholar)

Texas Instruments (1998 sabbatical)

Intel (1997 summer)

Research Summary:

A principal interest in Dr. Holtz’ research is the study of optical properties of group-III-nitride semiconductors. Our work concerns both fundamental optical and vibrational processes in these materials and applications to the relationship between growth approach, micro- and nano-scale structure, and material properties. We use photoluminescence (spectroscopy and time-resolved emission) to examine optical transitions and the effects of temperature, pressure and stress on these processes. Understanding and accounting for these effects is critical for device design and performance. Visible and UV micro-Raman spectroscopy studies enable understanding of fundamental phonon processes, as well as the effects of stress and heating in device structures, which influence operating characteristics and can be a leading failure mechanism. [1-8]

Applied studies have been aimed at process development, such as plasma etching and device operation of semiconductor devices such as the heterojunction field-effect transistor based on GaN. We are specifically interested in the self-heating mechanisms of these devices, which degrades conductance and can eventually lead to device failure. To understand this failure mechanism, we developed UV Raman measurements as a way to determine temperature rise in the two-dimensional electron gas (2DEG) of these interesting structures. [9-12]

Research in thermal properties has led to innovative studies of the thermal conductivity of thin films and nanowires. In this work, the combination of simulation and systematic studies of device design have proven to be key partners in extracting meaningful results. In our study of supported aluminum nanowires, we observed the thermal conductivity to drop dramatically as size decreases. This drop in thermal conductivity results from parasitic losses to the substrate, which could only be fully understood through simulations tightly coupled to the experiments. [13-15]

Select references to this work: (Google Scholar web page)

[11]      "Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor" by I. Ahmad, Ph.D., Texas Tech University, 2005.
[12]      "Plasma etching of AlN/AlGaInN superlattices for device fabrication" by K. Zhu, V. Kuryatkov, B. Borisov, G. Kipshidze, S. A. Nikishin, H. Temkin, and M. Holtz. Appl. Phys. Lett. 81, 4688 (2002); http://dx.doi.org/10.1063/1.1527986
[18]      "Finite size effect on the phase transition of vanadium dioxide" by M. Nazari, Y. Zhao, V. Hallum, A. Bernussi, Z. Y. Fan, and M. Holtz. Appl. Phys. Lett. 103, 043108 (2013);http://dx.doi.org/10.1063/1.4816507
[20]      "Structural, electrical, and terahertz transmission properties of VO2 thin films grown on c-, r-, and m-plane sapphire substrates" by Y. Zhao, J. H. Lee, Y. H. Zhu, M. Nazari, C. H. Chen, H. Y. Wang, A. Bernussi, M. Holtz, and Z. Y. Fan. J. Appl. Phys. 111, 053533 (2012);http://dx.doi.org/10.1063/1.3692391
 

 

  1. "Temperature and excitation intensity dependence of photoluminescence in AlGaN quantum wells with mixed two-dimensional and three-dimensional morphology" by G. Rajanna, W. Feng, S. Sohal, V. V. Kuryatkov, S. A. Nikishin, A. A. Bernussi, and M. Holtz. J. Appl. Phys. 110, 073512 (2011); http://dx.doi.org/10.1063/1.3645044
  2. "GaN stripes on vertical {111} fin facets of (110)-oriented Si substrates" by V. V. Kuryatkov, W. Feng, M. Pandikunta, J. H. Woo, D. Garcia, H. R. Harris, S. A. Nikishin, and M. Holtz. Appl. Phys. Lett. 96, 073107 (2010); http://dx.doi.org/10.1063/1.3310279
  3. "Selective area epitaxy of InGaN quantum well triangular microrings with a single type of sidewall facets" by W. Feng, V. V. Kuryatkov, S. A. Nikishin, and M. Holtz. J. Crystal Growth, Vol. 312, Issue 10, 1 May 2010, Pages 1717–1720;link to journal
  4. "Time-resolved photoluminescence studies of AlGaN" by G. Rajanna. M.S., Electrical and Computer Engineering, Texas Tech University, Lubbock, 2009.
  5. "Green light emission from InGaN multiple quantum wells grown on GaN pyramidal stripes using selective area epitaxy" by W. Feng, V. Kuryatkov, A. Chandolu, D. Y. Song, M. Pandikunta, S. Nikishin, and M. Holtz. J. Appl. Phys. 104, 103530 (2008); http://dx.doi.org/10.1063/1.3029695
  6. "Effect of stress and free-carrier concentration on photoluminescence in InN" by D. Y. Song, M. E. Holtz, A. Chandolu, A. Bernussi, S. A. Nikishin, M. W. Holtz, and I. Gherasoiu. Appl. Phys. Lett. 92, 121913 (2008); http://dx.doi.org/10.1063/1.2899941
  7. "Optical phonon decay in bulk aluminum nitride" by D. Y. Song, M. Holtz, A. Chandolu, S. A. Nikishin, E. N. Mokhov, Y. Makarov, and H. Helava. Appl. Phys. Lett. 89, 021901 (2006); http://dx.doi.org/10.1063/1.2219092
  8. "The influence of phonons and phonon decay on the optical properties of GaN" by D. Y. Song, M. Basavaraj, S. Nikishin, M. Holtz, V. Soukhoveev, A. Usikov, and V. Dmitriev. J. Appl. Phys. 100, 113504 (2006); http://dx.doi.org/10.1063/1.2361159
  9. "Optical Properties of a Nanoporous Array in Silicon" by L. Tian, K. Bhargava Ram, I. Ahmad, L. Menon, and M. Holtz. J. Appl. Phys. 97, 026101 (2005); http://dx.doi.org/10.1063/1.1831541
  10. "Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor using ultraviolet micro-Raman scattering" by I. Ahmad, V. Kasisomayajula, M. Holtz, J. M. Berg, S. R. Kurtz, C. P. Tigges, A. A. Allerman, and A. G. Baca. Appl. Phys. Lett. 86, 173503 (2005); http://dx.doi.org/10.1063/1.1906305 
  11. "Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor" by I. Ahmad, Ph.D., Texas Tech University, 2005.
  12. "Plasma etching of AlN/AlGaInN superlattices for device fabrication" by K. Zhu, V. Kuryatkov, B. Borisov, G. Kipshidze, S. A. Nikishin, H. Temkin, and M. Holtz. Appl. Phys. Lett. 81, 4688 (2002); http://dx.doi.org/10.1063/1.1527986
  13. "A Microelectrothermal Bridge Circuit with Complementary Parameter Estimation Algorithm for Direct Measurement of Thermal Conductivity" by N. Stojanovic, J. M. Berg, D. H. S. Maithripala, and M. Holtz. Journal of Microelectromechanical Systems p. 265, Volume:19, 2010; link to journal
  14. "Direct measurement of thermal conductivity of aluminum nanowires" by N. Stojanovic, J. M. Berg, D. H. S. Maithripala, and M. Holtz. Appl. Phys. Lett. 95, 091905 (2009); http://dx.doi.org/10.1063/1.3216035
  15. "Thin-film thermal conductivity measurement using microelectrothermal test structures and finite-element-model-based data analysis" by N. Stojanovic, J. S. Yun, E. B. K. Washington, J. M. Berg, M. W. Holtz, and H. Temkin. Journal of Microelectromechanical Systems, p. 1269, Vol. 8, 2007; link to journal
  16. "Tunable dual-band terahertz metamaterials bandpass filter" by Y. Zhu, S. Vargesna, Y. Zhou, V. Kuryatkov, M. Holtz, Z. Fan, M. Saed, and A. A. Bernussi. Optics Letters, Vol. 38, Issue 14, pp. 2382-2384 (2013);
 
http://dx.doi.org/10.1364/OL.38.002382
  17. "Temperature dependence of the optical properties of VO2 deposited on sapphire with different orientations" by M. Nazari, Y. Zhao, V. V. Kuryatkov, Z. Y. Fan, A. A. Bernussi, and M. Holtz. Phys. Rev. B 87, 035142 (2013); link to journal.
  18. "Finite size effect on the phase transition of vanadium dioxide" by M. Nazari, Y. Zhao, V. Hallum, A. Bernussi, Z. Y. Fan, and M. Holtz. Appl. Phys. Lett. 103, 043108 (2013); http://dx.doi.org/10.1063/1.4816507
  19. "Effect of substrate orientation on terahertz optical transmission through VO2 thin films and application to functional antireflection coatings" by Y. H. Zhu, Y. Zhao, M. Holtz, Z. Y. Fan, and A. A. Bernussi. Journal of the Optical Society of America B, Vol. 29, Issue 9, pp. 2373-2378 (2012); link to journal.
  20. "Structural, electrical, and terahertz transmission properties of VO2 thin films grown on c-, r-, and m-plane sapphire substrates" by Y. Zhao, J. H. Lee, Y. H. Zhu, M. Nazari, C. H. Chen, H. Y. Wang, A. Bernussi, M. Holtz, and Z. Y. Fan. J. Appl. Phys. 111, 053533 (2012); http://dx.doi.org/10.1063/1.3692391
  21. "Influence of defects on structural and electrical properties of VO2 thin films" by C. H. Chen, Y. Zhao, X. Pan, V. Kuryatkov, A. Bernussi, M. Holtz, and Z. Y. Fan. J. Appl. Phys. 110, 023707 (2011); http://dx.doi.org/10.1063/1.3609084