Research On MOCVD In Situ Photoluminescence And On-line Infrared Thermometry

In situ monitoring can improve product yield rate and optimize fabricationtechnology during growth of epitaxial wafer by MOCVD. Therefore, it is necessary toresearch and development in situ monitoring, with the development of the homemadeMOCVD equipment. In this paper, in situ measurement PL approach was presentedfor LED wafer of Si substrate InGaN/GaN MQW by special optical designing anddeliberately cooling the MOCVD reactor. Meanwhile, a design scheme was presentedfor a new multi-functional MOCVD infrared radiation thermometer probe. Thisthermometer can measure five result at the same time, two single-wavelength (940nmand1550nm) temperatures, one dual wavelength colorimetric temperature and twolaser interferometer curves (940nm and1550nm), respectively. A portable correctiontool has been developed using correct the actual window area of and launch standardtemperature scale during MOCVD reactor infrared thermometry. Lastly, the effect ofreactor technics parameters on grahite plate surface temperatures were investigatedusing independent design movable at radial single-wavelength infrared thermometer.All research above can provide:1) In situ PL measurement equipment was used to monitor PL spectra duringgrowth of GaN MQW on silicon (111) substrate by MOCVD. We found that thePL intensity of n-GaN layer gradually increased with a rise of temperature in therange from290to500oC. The peak wavelength of the yellow band was almostunaffected by temperature variations whether p-layer was present or not.However, the presence of the p-GaN layer significantly decreased the intensityof both the yellow band and MQW PL. Some findings in this paper may behelpful to understand the mechanism of yellow impurity band.2) In order to satisfy accuracy requests, reflectance must be correct for the threeradiation pyrometers. Moreover, dual wavelength colorimetric radiationthermometer has advantage of high precision, simple correction and minorinfluence from emissivity by theory analysis. 3) The grahite plate surface temperatures be affected, because of the thermalconductivity varies for different gases at MOCVD reactor. However, the gastotal amount does`t affect largely on temperature.