Wide Band Gap Semiconductors Group at YSU
A Wide Band Gap (WBG) semiconductor in general terms can be defined as a semiconductor with an energy band gap (EG) above 2 eV. Included in this group are the group III-nitrides, silicon carbide (SiC), zinc selenide (ZnSe) etc. The focus of our group is on the group III-nitrides, silicon carbide and zinc oxide.

Why Wide Band Gap Semiconductors?
                                                                                                                                                                                                                         
Present-day commercial satellites, modern jet aircrafts, automobile engines, sub-sea well logging systems, etc require thermal radiators to dissipate heat generated by the functional electronics. High temperature electronic systems for such functions require electronic devices that retain their functions and reliabilities up to the desired operation temperature as well as an interconnection technology on a substrate to form an electronic circuit with long-term operation capability. Currently, these electronics are based on traditional semiconductors such as silicon or gallium arsenide, which would fail if they were not properly cooled. The cooling system introduces serious drawbacks including addition of a substantial amount of weight, which lowers the efficiency and reliability of the devices. As a result, wide band gap semiconductors such as group III-nitrides, silicon carbide and zinc oxide have recently attracted a great deal of attention. These semiconductors offer the possibility of realizing exciting new electronic devices for high power, high temperature and high frequency operations enabling substantial savings, increased performance and reliability. The III-nitrides and zinc oxide in particular can be used in a variety of opto-electronic devices operating in shorter wavelength regions than could be possible with silicon or gallium arsenide.

Group III-nitrides:
The group III-nitrides comprise gallium nitride (GaN, EG = 3.4 eV), aluminum nitride (AlN, EG = 6.2 eV) indium nitride (AlN, EG = 0.8 eV) an their alloys.

Silicon carbide:
 Silicon carbide (SiC) exists as a family of crystals known as polytypes. The difference among the polytypes is in the arrangement of layers of silicon (Si) and carbon (C) and over 200 polytypes of SiC are known to exist. Only one cubic (zincblende) polytype 3C, with EG = 2.39 eV exists and the rest are hexagonal (wurtzite). Of the wurtzite polytype, the important ones are 4H  (with EG = 3.27 eV) and 6H (with EG = 3.02 eV). Silicon carbide possesses extremely high thermal, chemical, and mechanical stability. Its extreme mechanical stability is the reason for its use as a coating for drill bits and saw blades. Because of its large band gap energy, the thermal generation of electron-hole pairs  in SiC is many orders of magintude lower at any given temperature compared to silicon. This makes it possible to build "dynamic" memories (DRAMs) in SiC that only need to be refreshed about once every 100 years at room temperature! This also makes it possible to operate SiC devices at temperatures as high as 650 °C without degradation in electrical performance. The breakdown electric field in SiC is about 8 times higher than in silicon, making SiC very attractive for fabricating high-voltage power switching transistors.


Collaboration with our group:
At present, we have collaboration with the GaN group at Kansas State University and with the Condensed Matter group at Auburn University. We warmly welcome collaboration with other groups working in this field and we encourage you to contact Dr. Tom N. Oder (tnoder@ysu.edu).


Research Facilities


Mask Aligner with resolution of 2 µm
                     De-Ionized Water System



Sputter Deposition System, CVC Products, Inc., Model SC-3000

 Base Pressure of the System



Base Substrate Temperature



Rapid Thermal Processor

Thermal Evaporation and Vacuum Annealing System, Key High Vacuum Products, Model KV-301



Pam Using I-V Characterization System

Resist Spin Coater
 


STUDENTS



Pamela Martin at the Mask Aligner


Matt Crummel at the Sputter Coater



Snowflake Kicovic

Loren Webb


Condensed Matter Physics Class 5830

Manam


Mark Barlow

Edward Sutphin


Aaron Schott

Sara Schaefer

Rani
Rani  Kummari
Mark Del Fraino
Mark Del Fraino


Dr. Ta-Lun (Jeff) Sung
Dr. Ta-Lun Sung
STEMM1
Dr. Oder with High School students

James1
James Aldridge









Kurtis Townsend (picture coming soon)


Snowflake Kicovic (Senior in Physics and Computer and Electrical Engineering)
Pamela Martin:  (Junior in Physics)
  Loren Webb: (Senior in Physics and Mathematics)

Matt Crummel: (Junior in Physics)

In the News
Jimdoc1  Jimdoc2    Timdoc1  


YSU Frontiers: Summer 2005


Dr. Tom Oder and student Pam Martin work at the YSU Sputter Deposition System.

Recipients of Dean’s Awards at YSU’s eighth annual Research Recognition Luncheon in Kilcawley Center. From the left are Tom Oder, assistant professor of physics and astronomy, who received the award for the “Most Prolific New Investigator in Applying for External Funding;” Greg Sturrus, chair of the Department of Physics and Astronomy, who accepted the award for the department showing “Superior Success in Obtaining External Funding;” and Rangamohan Eunni and Rammohan Kasuganti of the management department, who received the award for faculty members demonstrating “Superior Success in Obtaining External Funding.

CLiPS
Jim Andrews, left, and Tom Oder, faculty members in YSU’s physics department, are joined by student Jessica Simpson in a lab in the basement of Ward Beecher Hall. The three are part of YSU's new and prestigious affiliation with the National Science Foundation's Center for Layered Polymeric Systems. For the rest of the story, click the link YSUpdate News March 4, 2008

Links to Vendors
1. Myres Vacuum
2. Kurt J. Lesker