Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Compound semiconductor

Sapphire substrate material growth of high quality AlN

Author FengChao
Tutor ChenChangQing
School Huazhong University of Science and Technology
Course Optical Engineering
Keywords AlN The buffer layer Epitaxial layer Crystal quality Surface morphology
CLC TN304.2
Type Master's thesis
Year 2011
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Ⅲ nitride its excellent characteristics have been widespread concern , AlGaN material system corresponding emission wavelength at 210-340nm, fit can be applied to white lighting , biochemical detection, disinfection and purification fields of ultraviolet light-emitting devices become a research hotspot. The AlGaN material, due to the lack of single crystal , the general growth of AlN as a template . Therefore, to obtain high-quality production of the device for AlGaN materials, preparation to become high-quality AlN material must first be solved. Heteroepitaxial AlN films , often using SiC, Si or sapphire as a substrate material . The AlN and these materials do not match, the crystal quality is poor. This paper focuses on the growth of high quality AlN materials commenced a two-step growth method , the main parameters of the buffer layer growth of epitaxial layers . First, the principle elaborated MOCVD growth , characterization used in this experiment equipment HR-XRD, AFM , etc., and data processing methods . According to the material properties of AlN , analyzing substrate selection, surface preparation , reaction chamber pressure , V / III ratio on the growth of AlN , determine the relevant growth parameters . Then explore the buffer layer growth temperature on the crystalline quality of the epitaxial layer and the surface morphology . At 600 ℃ ~ 870 ℃ range selected six samples grown at different temperatures , while keeping other growth parameters unchanged. With transmission spectra , AFM, HR-XRD and other testing , found in the 690 ℃ ~ 780 ℃ when the surface atomic steps, especially in the 780 ℃, the crystal quality is better . Low temperature , the dislocation density ; high temperature , surface roughness , there are many pits . Further changes to the buffer layer growth time to study the effect of the thickness of the buffer layer . Three samples grown , the growth time of 4.4 minutes, the sample ( 0002) FWHM of 116arcsec, (1012) plane FWHM of 1471arcsec, and the surface atomic steps . The thick epitaxial layer is thinner , the surface steps were not there , the crystal quality and surface morphology were poor. According to results of these two experiments , the buffer layer of the epitaxial layer of the mechanism . Finally, the growth of the previous experiment template better , growing a high temperature continuous manner using AlN. Through two experiments , at different growth temperatures , changing TMAl and NH3 flow rate , V / III ratio to the preliminary study on the continuous growth mode AlN quality.

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