The study of SiO2/InSb structure fabricated by PECVD
인듐안티모나이드 적외선감지소자용 SiO2 절연막에 대한 연구

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서울대학교 대학원
학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2012. 2. 윤의준.
Most Ⅲ-Ⅴ compound semiconductors are widely used for electric and optical devices. In infrared image system, Indium antimonide (InSb) has received strong attention as a high quality photo-detector which requires a low dark current due to advantages of narrow band gap (0.228 eV) energy and high electron mobility of up to 106 cm2/Vs at 77 K. However, InSb has some disadvantages to apply for the infrared image systems that it has a high evaporation of group Ⅴ element and its surface can be easily damaged by ion bombardment. They generally cause the excess leakages affect to degrade the device performances. In order to reduce dark current, the surface of the InSb must be deposited with an adequate dielectric layer with the minimum interface state density and fixed charge density. However, passivation layers to suppress dark currents are still bottle-neck for high performance detector and technology to control the interface between passivation layer and semiconductor is not well established.
In this study, SiO2 layers were deposited by plasma enhanced chemical vapor deposition (PECVD) with various temperature and other variables and then annealed in N2 ambient with other temperature and time. Capacitance-Voltage, XPS, FT-IR, Raman analysis proceeded. In C-V curve, fixed charge and interface traps were calculated for each sample. In XPS analysis, quantity of In oxide and Sb oxide at the interface between SiO2 and InSb was relatively calculated. In FT-IR analysis, peak position of Si-O-Si stretching mode(ν=1065cm-1 : value for thermally grown SiO2) give me many things (angle of Si-O-Si, film quality, etc). In raman analysis, we can find out presence of elemental Sb in the sample.
The sample deposited at 250 oC has the lowest bulk trap density and the lowest interface trap density (Dit). With the higher deposition temperature, both In oxide and Sb oxide increase and the angle of O-Si-O increase and film quality increase. Elemental Sb is present in the sample deposited above 300 oC.

When other variables (frequency, power, pressure, flow ratio of N2O/SiH4) were increased, all samples dont have elemental Sb and C-V curve shifted to the positive voltage. 13.56 MHz is better than 187 kHz for SiO2 film quality and 90 watt as rf power is better than other rf powers for SiO2 film quality. 550 mTorr as pressure is better than other pressures for SiO2 film quality and 1700 sccm/160 sccm as flow ratio of N2O/SiH4 is better than other flow ratios for SiO2 film quality.

N2 annealing increases film quality of SiO2. N2 annealing at 100 oC, 150 oC doesnt make many changes of C-V curve. But 250 oC annealing makes the C-V curve shifted to negative voltages.
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Materials Science and Engineering (재료공학부)Theses (Master's Degree_재료공학부)
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