Thermoluminescence assessment of 0.5, 1.0 and 4.0 µm thick HFCVD undoped diamond films

Abstract

AbstractChemical vapor deposition (CVD) diamond has not found extensive application as a thermoluminescence (TL) dosimeter, mainly because its TL glow curve shape is not reproducible. A slight variation in the growing conditions may result in strong changes in the morphology, microstructure, and surface‐impurity‐related defects, considerably affecting the TL glow curve features. In order to study the main TL characteristics under controlled growing conditions, we present results on three 0.5, 1.0, and 4.0 µm thick hot filament CVD (HFCVD) diamond films grown on Si (100) substrates. The recorded TL glow curves were resolved into individual peaks by a home‐made deconvolution program and the kinetic parameters of the peaks were extracted. The best fits of the TL glow curves were obtained using four peaks, except for the 4.0 µm thick sample that required five TL components. All samples showed three high intensity TL peaks between 180–400 °C and a less intense one or two peaks in the 100–180 °C low‐temperature region. The low‐temperature components all obey second‐order kinetics while the high‐temperature ones obey first and 1.6 order kinetics. The samples showed similar TL peaks with comparable kinetics parameters. It is concluded that the manufacturing of high quality HFCVD diamond may require a further improvement in the growing process in order to exploit its excellent tissue‐equivalence properties in clinical and medical applications.