高能分辨率深能级瞬态谱仪器(DLTS)摘要.ppt

DLTS Presentation Deep Level transient Spectroscopy Pioneers in Measurements of Depth *picture taken from Serway, Raymond A., Beichner, Robert J. and Jewett, John W. Physics for Scientists and Engineers 5th Edition, Saunders College Publishing: Orlandon, FL, 2000 Motivation: Measuring the Depth of Defect –Related Traps in Semiconductors Carrier Trapping Conductance Band Valence Band Defect Level Trap depth Energy - Carrier Escape kT Low Temperature kT slow fast High Temperature - - History of DLTS The DLTS Technique was developed in 1974 by D V Lang as an extension to traditional Thermally Stimulated Transient Capacitance (TSCAP). It is now well established as a method to quantify electrically active deep levels. It is complementary to other analytical techniques such as SIMS How are these levels characterized? The levels are characterized by a “Fingerprint” which includes: Energy Concentration (amount of defects present) Capture Cross Section (effectiveness of the level) a) Schottky barrier under reverse bias VR b) Schottky barrier with fill pulse applied. Deep levels forced under the Fermi level fill with carriers c) Thermal emission of carriers from filled deep levels now above the Fermi level as the full pulse ends d) Capacitance changes observed as the bias on the test sample is changed ? = full deep level ? = empty deep level (a) (b) (c) Vp VR Automatic Arrhenius Plot Digital DLTSIsothermal Applications Fully automated and VERY FAST trap profiling with depth: varying pulse bias, reverse bias or both capture cross section with pulse widths to 8ns possible ICTS - like analysis (variation of Tw and temperature) for a thorough and accurate investigation of a single isolated DLTS peak for extending cryostat range for measuring temperature sensitive devices Digital DLTSMOS/MIS Application MOS/MIS measurement and evaluation using by pulsed C-V and DLTS in addition to Zerbst Analysis (C-t characterisation)