Skip navigation to main content. National Renewable Energy Laboratory (NREL)NREL HomeInnovation for Our Energy Future
About NRELScience and TechnologyTechnology TransferApplying TechnologiesLearning About Renewables
Measurements and Characterization
Photovoltaic Research Measurements & Characterization Measurements and Characterization Home About Measurements & Characterization Analytical Microscopy Device Performance Measurement Electro-Optical Characterization Photoluminescence Spectroscopy Minority-Carrier Lifetime Spectroscopy Fourier-Transform Infrared & Raman Spectroscopy Spectroscopic Ellipsometry Capacitance Techniques Scanning Defect Mapping Reflectance Spectroscopy Computational Modeling Surface Analysis Research Staff Working with Us

Capacitance Techniques

Deep-level transient spectroscopy generated graph showing six defect levels; DLTS signal (Y-axis) versus Temperature (X-axis).

DLTS characterizes defect levels to assist in identification of impurities and potential recombination centers.

Capacitance techniques monitor the movement of electronic charge within a semiconductor device and provide a measure of free-carrier and electrically active defect-state properties. Capacitance is the charge storage capacity and is measured across a rectifying junction.

Applications

Capacitance-voltage Measurements

Determines the concentration of majority carriers in the bulk of the device, energy levels of interface states (or both) that often exist between the surfaces of dissimilar materials.

Deep-level Transient Spectroscopy (DLTS)

Examines the time-dependent flow of charge into and out of localized energy states associated with defects in the semiconductor. DLTS can detect trap concentrations as low as 1012 cm-3 and as high as the doping level (constant-capacitance DLTS). It also distinguishes between minority- and majority-traps; determines activation energy and captures cross-section. Our capabilities allow the use of electrical or optical pulses to fill traps and a sample temperature range of ~20 to 475 K. DLTS is a nondestructive complement to secondary-ion mass spectrometry and Auger electron spectroscopy.

Admittance Spectroscopy

Characterizes defect levels by measuring capacitance with varying frequency and temperature.

For additional information contact Brian Keyes, 303-384-6695.