Study On The Epitaxial Growth Of Alxga1-xn By MOCVD And Fabrication Of Solar-blind P-i-n Focal Plane Array Photodetector

Ternary alloy crystal material Al_xGa_1-xN,synthetized by GaN and AlN, not only has wide band gap, but also its direct band gap is continuously adjustable between 3.4ev and 6.2ev along with its Al content changing. The corresponding absorption optical wavelength is between 200nm and 365nm and the solar-blind detectors working at the wavelength of 240～280nm, which can be widely used for biochemical analysis, ozone monitoring, UV communication, solar illumination monitoring, fire monitoring, etc, have attracted much attention in and abord.For this dissertation, firstly, principles of the epitaxial growth of Al_xGa_1-xN by MOCVD,relevant physiochemical processes and existing problems are presented. Then experiments are carried out to make researches on the epitaxial growth process which involves the following problems: choice of substrate, epitaxial growth of AlN buffer layer and Al_xGa_1-xN/AlN superlattice buffer layer, high Al content Al_xGa_1-xN material by MOCVD and its n-type dope. Finally, a 320×256 Al_xGa_1-xN solar-blind p-i-n focal plane array(FPA) photodetector is fabricated, its electrical property and spectral response are tested and imaging demonstrations are performed. Main conclusions are obtained as follows:Ⅰ. The FWHM values of X-ray rocking curves (XRC) of (0002)plane and (10-12)plane of AlN template are 37 arcsec and 712 arcsec, respectively. And AFM test indicates atomic flat surface is obtained. Al_xGa_1-xN/AlN superlattice is grown sucessfully.Ⅱ. The FWHM value of (0002)plane of Al_xGa_1-xN with the Al content higher than 0.6 is 213 arcsec; and its n-type carrier concentration is 6.9×10¹⁸cm^-3 and carrier mobility at room temperature is higher than 50.0cm2/v.s. test results indicate that every parameter of the grown material can basically meet the requirements of device fabrication, and expitaxial material growth of back-illuminated p-i-n UV detectors is paid attention to.Ⅲ. The spectral response range of the fabricated photodetector is 250²80nm which belongs to solar-blind range; Under 2 volt reverse bias, the peak response is achieved at the wavelength around 265nm and the responsivity is 0.15A/W and the quantum effciency is 63%; Under 3 volt reverse bias, the dark-current is 6.5nA/cm², and the peak detectivity is 3.63×10¹³cm^·Hz^1/2/W.