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Washington State University Institute of Materials Research

Crystal Characterization and Spectroscopy

Materials grown at WSU are characterized by various techniques to determine electrical, optical, and structural qualities. Below is a summary of the various techniques we routinely use, categorized as electromagnetic measurements, defect spectroscopy, broadband spectroscopy, and imaging.

Below we summarize abbreviation, full name, and utility of the various measurements, as well as some details on the temperature and wavelength ranges as applicable. Further details on individual techniques can be found in accompanying links.

Electrical Measurements UtilityTemperature Range (K)
HallHall Effect, ResistivityIdentification of charge-state transitions; carrier density, mobility80 – 700
I-VCurrent-VoltageInvestigation of Ohmic and Schottky contacts, photoconductivity
C-VCapacitance-VoltageCharacterization of semiconductor devices
FWHMDetector ResolutionRadiation detector absolute performance quantification300
Mu-TauMobility-LifetimeRadiation detector relative performance quantification300

Defect Spectroscopy UtilityTemperature Range (K)Wavelength Range
TEES, TSCThermo-Electric Effect Spectroscopy, Thermally Stimulated CurrentElectrical measurements assessing energetic location of deep levels “near” (<~1.2 eV) and far from band edges; measures current10 – 350365 nm, 385 nm, 400 nm, 780 nm, 950 nm diode excitation
DLTS, ODLTS, PICTSDeep level transient (optical) spectroscopy, deep level optical spectroscopy, photo-induced current spectroscopyElectrical measurement assessing energetic location of deep levels “near” (<~1.2 eV) and far from band edges; measures capacitance or current
80 – 490340 nm, 365 nm, 405 nm diode excitation
TL, TSLthermoluminescence, thermally stimulated luminescenceThermal release of traps; emission energies associated with excitation to/from deep levels to the host band edges or other defects20 – 300 and 300 – 673400 – 1300 nm
PL, PLEphotoluminescence, photoluminescence excitationOptical absorption and release of traps; emission energies associated with excitation to/from deep levels to the host band edges or other defects4 – 400200 – 800 nm excitation; 300 – 850 emission
PASpositron annihilation spectroscopyIdentification and characterization of neutral and negatively charged vacancies and related defects as a function of depth and nearby atoms; measure diffusion length of positrons
300-1273
0 - 70 keV monoenergetic beam

Broadband Spectroscopy UtilityTemperature Range (K)Wavelength Range
IR spectrometerinfrared absorption, transmissionOptical measurement of electronic and vibrational polarization, obtained in transmission or absorption10 – 450500 – 8000 cm-1
FTIRFourier Transform InfraredOptical measurement of vibrational polarization, obtained in attenuated total reflectance300375 – 7500 cm-1
UV-VISultraviolet-visibleOptical measurement of electronic polarization, obtained intransmission, absorption, total integrated scatter; can be used for powders, liquids273 – 373 190 – 1100 nm
UV-VIS-NIRultraviolet-visible-near infraredElectronic and vibrational polarization, obtained in transmission or absorption; optimized for thin windows300175 – 3300 nm
BWObackwards wave oscillatorHigh frequency quasi-optical transmission measurements at millimeter wave frequencies30035-55 GHz, 170-270 GHz

Imaging UtilityTemperature Range (K)Wavelength Range
InfraredInfrared imaging300850nm
RamanRaman mapping300-1700455 nm - 785 nm excitation
OpticalTransmission, reflection, polarization visible imaging300-1700visible light
X-rayX-ray nano-tomography300Cr X-ray tube

Laboratories:  EME B6, ETRL 345, Webster G36