Relaxation of excited surface states of thin Ge-implanted silica films probed by OSEE spectroscopy

• Published in: Journal of luminescence Vol. 169; pp. 143 - 150
• Main Authors: Zatsepin, A.F., Buntov, E.A., Mikhailovich, A.P., Slesarev, A.I., Schmidt, B., von Czarnowski, A., Fitting, Hans-Joachim
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2016
• Subjects: Electron emission; Energy structure; Ion implantation; Relaxation; Surface states; Thin films; Thin films; Relaxation; Ion implantation; Electron emission; Energy structure; Surface states
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2015.08.073

As an example of thin silica films, 30nm SiO2–Si heterostructures implanted with Ge+ ions (1016cm−2 fluence) and rapid thermally annealed (RTA) at 950°C are studied by means of optically stimulated electron emission (OSEE) in the spectral region of optical transparency for bulk silica. Quartz glass samples were used as references. Experimental data revealed a strong dependence between electron emission spectral features and RTA annealing time. The spectral contributions of both surface band tail states and interband transitions were clearly distinguished. The application of emission Urbach rule as well as Kane and Pässler equations allowed to analyze the OSEE spectra at different optical excitation energy ranges and to retrieve the important microstructural and energy parameters. The observed correlations between parameter values of Urbach- and Kane-related models suggest the implantation-induced conversion of both the vibrational subsystem and energy band of surface and interface electronic states. •Peculiarities of electron emission from excited surface states of SiO2:Ge structures are studied.•Spectral contributions of surface band tails and interband transitions are distinguished.•Urbach and Kane models allow to examine photo-thermal emission mechanism.•Surface energy gap and structural disorder parameters are determined.