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		Utility	Temperature Range (K)
Hall	Hall Effect, Resistivity	Identification of charge-state transitions; carrier density, mobility	80 – 700
I-V	Current-Voltage	Investigation of Ohmic and Schottky contacts, photoconductivity
C-V	Capacitance-Voltage	Characterization of semiconductor devices
FWHM	Detector Resolution	Radiation detector absolute performance quantification	300
Mu-Tau	Mobility-Lifetime	Radiation detector relative performance quantification	300

Defect Spectroscopy		Utility	Temperature Range (K)	Wavelength Range
TEES, TSC	Thermo-Electric Effect Spectroscopy, Thermally Stimulated Current	Electrical measurements assessing energetic location of deep levels “near” (<~1.2 eV) and far from band edges; measures current	10 – 350	365 nm, 385 nm, 400 nm, 780 nm, 950 nm diode excitation
DLTS, ODLTS, PICTS	Deep level transient (optical) spectroscopy, deep level optical spectroscopy, photo-induced current spectroscopy	Electrical measurement assessing energetic location of deep levels “near” (<~1.2 eV) and far from band edges; measures capacitance or current	80 – 490	340 nm, 365 nm, 405 nm diode excitation
TL, TSL	thermoluminescence, thermally stimulated luminescence	Thermal release of traps; emission energies associated with excitation to/from deep levels to the host band edges or other defects	20 – 300 and 300 – 673	400 – 1300 nm
PL, PLE	photoluminescence, photoluminescence excitation	Optical absorption and release of traps; emission energies associated with excitation to/from deep levels to the host band edges or other defects	4 – 400	200 – 800 nm excitation; 300 – 850 emission
PAS	positron annihilation spectroscopy	Identification 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		Utility	Temperature Range (K)	Wavelength Range
IR spectrometer	infrared absorption, transmission	Optical measurement of electronic and vibrational polarization, obtained in transmission or absorption	10 – 450	500 – 8000 cm-1
FTIR	Fourier Transform Infrared	Optical measurement of vibrational polarization, obtained in attenuated total reflectance	300	375 – 7500 cm-1
UV-VIS	ultraviolet-visible	Optical measurement of electronic polarization, obtained intransmission, absorption, total integrated scatter; can be used for powders, liquids	273 – 373	190 – 1100 nm
UV-VIS-NIR	ultraviolet-visible-near infrared	Electronic and vibrational polarization, obtained in transmission or absorption; optimized for thin windows	300	175 – 3300 nm
BWO	backwards wave oscillator	High frequency quasi-optical transmission measurements at millimeter wave frequencies	300	35-55 GHz, 170-270 GHz

Imaging		Utility	Temperature Range (K)	Wavelength Range
Infrared		Infrared imaging	300	845 nm or 941 nm
Raman		Raman mapping	300-1700	455 nm - 785 nm excitation
Optical		Transmission, reflection, polarization visible imaging	300-1700	visible light
X-ray		X-ray nano-tomography	300	Cr X-ray tube

Laboratories:  EME B6, ETRL 345, Webster G36