tailieunhanh - Báo cáo hóa học: " Deep Level Transient Spectroscopy in Quantum Dot Characterization"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Deep Level Transient Spectroscopy in Quantum Dot Characterization | Nanoscale Res Lett 2008 3 179-185 DOI S11671-008-9133-5 NANO EXPRESS Deep Level Transient Spectroscopy in Quantum Dot Characterization O. Engstrom M. Kaniewska Received 11 March 2008 Accepted 5 May 2008 Published online 28 May 2008 to the authors 2008 Abstract Deep level transient spectroscopy DLTS for investigating electronic properties of self-assembled InAs GaAs quantum dots QDs is described in an approach where experimental and theoretical DLTS data are compared in a temperature-voltage representation. From such comparative studies the main mechanisms of electron escape from QD-related levels in tunneling and more complex thermal processes are discovered. Measurement conditions for proper characterization of the levels by identifying thermal and tunneling processes are discussed in terms of the complexity resulting from the features of self-assembled QDs and multiple paths for electron escape. Keywords Electron states in low-dimensional structures Quantum dots III-V semiconductors Electrical properties Deep level transient spectroscopy Introduction Deep level transient spectroscopy DLTS is a technique for filtering signal transients from the emission of charge carriers at localized band gap energy levels to the conduction or valence band of semiconductors. Performing measurements for varying temperature the method was developed to transfer data from the time domain into O. Engstrom El Microtechnology and Nanoscience Chalmers University of Technology 412 96 Goteborg Sweden e-mail M. Kaniewska Department of Analysis of Semiconductor Nanostructures Institute of Electron Technology Al. Lotnikow 32 46 02-668 Warsaw Poland temperature spectra with characteristic features that can be used to identify properties of deep energy levels in semiconductors 1 . When using DLTS to investigate emission properties of charge carriers in quantum dots QDs additional problems occur due to the specific properties connected with this kind of .