C-DLTS Principle of operation and limits of application课件.ppt

C-DLTS Principle of operation and limits of application E. Fretwurst Institute for Experimental Physics, University of Hamburg Principle of operation and basics The C-DLTFFT-System at HamburgDifferent hardware toolsPrinciple of operationMethods of defect parameter evaluation, limits and systematic errorsHigh Resolution option, basics, an example and practical limits Summary 1 E. Fretwurst, University of Hamburg Workshop on Defects, Hamburg, August 23-2006 精品文档 Principle of Operation [1] Constant reverse bias (VR) traps empty traps filled Traps in the space charge region of a p+-n diode Left: Electron trap Right: Hole trap 2 E. Fretwurst, University of Hamburg Workshop on Defects, Hamburg, August 23-2006 Bias pulse Vp 0 Vp 0 Capacitance transients ?C(t) = C(t) – CR for t tp  negative positive [2] Carrier injection (Vp) electron capture hole capture [3] Thermal emission of trapped carriers (VR) electron emission hole emission 精品文档 Transient analysis Capacitance transient: ?C(t) = C(t) – CR = ?C0·exp(-(t+t0)/?e) Emisson time constant: 1/?e = en + ep for en ? ep ? 1/?e = en en,ep emission rates for electrons, holes From measured transients as function of T: ? ?e(T) values are extracted ? From Arrhenius plot activation energy Ea,n,p and capture cross section ?n,p can be extracted using: assuming ?n,p independent on T ? 3 E. Fretwurst, University of Hamburg Workshop on Defects, Hamburg, August 23-2006 Different DLTS techniques: Analog signal processing: double boxcar integrator lock-in amplifier analog correlator Digital signal processing: various correlator functions Fast Fourier Transformation FFT Laplace Transformation Refolding of “period scans” 精品文档 Determin