Transmission spectra of crystals at elevated temperatures for the calculation of internal radiant heat transport during crystal growth – Part 1: The spectrometer and its performance

Abstract

We report the construction, operation and performance of a transmission spectrometer for the visible to the IR (up to 3.5 µm wavelength) to measure crystals up to a temperature of 1400°C. The spectral resolution is almost comparable to that of a commercial spectrometer. The performance of the spectrometer and some problems are demonstrated by spectra of YAG : Nd at different temperatures.

Temperature-dependent optical absorption of SrTiO3

“…The light is passed through the furnace with the sample into an Oriel MS125 1/8 m grating spectrograph with a Si CCD detector for visible light, or into an Acton SpectraPro 2300i spectrograph with an InGaAs diode array for the infrared range. The spectrographs were placed at least a meter away from the sample to remove most of the unfocused thermal radiation (as discussed by Schwabe and Polity ()). The sample compartment can be flushed with different gases to investigate atmospheric influences.…”

Transmission spectra of crystals at elevated temperatures for the calculation of internal radiant heat transport during crystal growth – Part 2: Spectra of YAG:Cr, YVO4:Nd and the bandgap variation of various materials

“…With the transmission spectrometer described in part 1 [2] and according to the procedure described there we registered the following transmission spectra, corrected them and describe and discuss our observations. 2.1 YVO 4 :Nd, 2.5 mm thick Figure 1 shows transmission spectra of the 2.5 mm thick sample No 1 between 25° C and 1310° C. First of all we must admit that the spectra are very noisy below 400 nm because of insufficient intensity of the spectral source in this wavelength region.…”

“…predicting the most suitable thermal environment, the crystal rotation rate for flat interface growth, the maximum growth speed, …) the transmission data of the crystals at various temperatures up to the melting point are needed. We reported about a suitable spectrometer and data of YAG : Nd in part 1 of these papers [2]. In part 2 details of YVO 4 :Nd, YAG:Cr up to 1310° are given together with the temperature shift of the bandgaps of MnWO 4 , PbMoO 4 , CaWO 4 , and ZnS.…”

Spiral formation during Czochralski growth of rare-earth scandates

“…Consequently, the transmission spectra of the very same GdScO 3 , DyScO 3 , and SmScO 3 wafers were measured at elevated temperatures (1400 1C) between 450 and 900 nm (NdScO 3 will follow later) by a non-commercial spectrometer [40] (Fig. 3).…”