本文關鍵詞：碲鎘汞紅外光伏探測器電學性能表征技術研究　出處：《中國科學院研究生院(上海技術物理研究所)》2015年博士論文　論文類型：學位論文

  更多相關文章： 碲鎘汞紅外探測器 表面漏電流 MIS電容 非線性金屬半導體接觸

【摘要】：碲鎘汞半導體材料以其優(yōu)良的光電特性,自問世以來就成為制備高性能紅外探測器的重要材料。隨著第三代碲鎘汞紅外探測器技術的快速發(fā)展,低成本大規(guī)模焦平面芯片的制備需要更穩(wěn)定的工藝過程和更高芯片良品率,并且在航天遙感應用中,復雜的空間應用環(huán)境也對碲鎘汞光伏探測器芯片的可靠性提出了更高的要求。不論是工藝過程監(jiān)控、器件工藝改進還是芯片失效分析都要建立在探測器芯片各部分結構質量的準確表征的基礎上,同時需要定量化的參數分析方法,從多批次的測試結果中統(tǒng)計分析芯片各部分性能的變化趨勢,為器件工藝的持續(xù)改進、器件可靠性與穩(wěn)定性的提高提供有效的評價方法與定量化的分析手段。然而通常使用的微電子集成測試結構的物理模型、實驗數據分析方法是基于硅基器件特性建立的,并沒有考慮碲鎘汞光伏器件自身的獨特性質(禁帶寬度窄、載流子易簡并等)。本文針對影響碲鎘汞器件性能及長期可靠性的常見因素——表面漏電流、碲鎘汞-鈍化層界面狀態(tài)及金屬-碲鎘汞接觸,研究了柵控二極管、MIS電容器以及傳輸線測試結構,提出了相應的物理模型與數據分析方法,為這些測試結構在大規(guī)模碲鎘汞紅外探測器芯片中的應用奠定理論基礎。其主要研究內容如下:1.碲鎘汞柵控二極管與表面漏電機制。本文利用柵控二極管結構研究了表面勢對碲鎘汞光伏器件動態(tài)阻抗和暗電流的影響。提出了不同機制表面漏電的理論模型:表面積累時,用適當修正的隧穿電流模型來描述表面隧穿電流;表面強反型形成溝道時,利用傳輸線模型建立了表面溝道電流模型。通過選取適當的表面參數——平帶電壓VFB、表面缺陷密度Nst和溝道載流子遷移率μc,上述模型能夠較好的描述中波碲鎘汞光伏器件的優(yōu)值因子R0A和暗電流與表面勢的關系。實驗結果表明本文所提出的表面漏電流模型能夠比較好的描述和定量表征器件表面漏電特性,為進一步改進器件工藝提供了依據。2.金屬-絕緣層-碲鎘汞(MIS)器件電容理論與界面特性表征技術。針對碲鎘汞材料的特點,建立包含導帶非拋物和載流子簡并效應的泊松方程,并利用數值方法得到了碲鎘汞MIS器件高、低頻理想C-V曲線;總結了各種影響碲鎘汞MIS器件理想高低頻C-V曲線的因素;討論了碲鎘汞MIS器件中高頻C-V曲線的最小值與表面處理等工藝密切相關的事實,提出了一種等效高頻界面陷阱電荷模型來描述這一實驗現象,修正了用于提取界面態(tài)密度的理想高頻C-V曲線,使得提取的界面態(tài)密度的大小和在禁帶寬度內的分布更加合理。該理論和數值分析方法成功的應用于同批次MIS器件性能的監(jiān)控和不同工藝對MIS器件的影響。實驗測得Cd Te/Zn S雙層鈍化MIS器件的各項物理參數為:絕緣層固定電荷密度,絕緣層陷阱電荷密度,界面陷阱密度在能帶中的最小值,等效高頻界面陷阱密度。3.非線性金屬-半導體接觸表征技術。結合金屬-半導體接觸的電流輸運特性,綜合考慮了電流的聚集效應和金半接觸的整流效應,提出了非線性傳輸線模型;以熱電子發(fā)射為例,系統(tǒng)討論了非線性傳輸線模型描述的電極IV特性;分析了非線性傳輸線模型與線性傳輸線模型中電流傳輸長度的不同,新模型中的電流傳輸長度Ltg與流入電流相關,能夠更合理的描述電流在電極下的聚集效用,為碲鎘汞焦平面芯片的設計提供了指導。利用非線性傳輸線模型和相應的數據分析方法研究了Au/Sn/p-Hg Cd Te接觸的電學特性,得到了相關物理參量:肖特基勢壘高度、理想因子n=1.45、歐姆特性接觸電阻、電極下半導體薄膜電阻,電流傳輸長度Ltg在8~11μm之間并與流入電流有關。4.鈍化層電阻率測試方法研究。利用MIS結構研究了電子束蒸發(fā)制備的Cd Te/Zn S鈍化層電流-電壓特性和電阻率,其中高阻抗的柵電極占總數的62.5%,電阻率在之間。另外,本文利用鏡像電荷法模擬了四探針測試材料中的電勢場分布,分析了有限尺寸的探針對測量精度的影響。模擬結果指出,在無限厚材料上,常用的計算方法只有在探針間距與探針直徑的比值大于3的時候才能得到準確的材料電阻率(相對誤差小于1%);在有限厚材料上,由近似公式引入的誤差遠大于探針尺寸引入的誤差,在需要精確計算材料電阻率的情況下需要通過數值模擬精確分析。該研究結果為四探針法在微區(qū)鈍化層電阻率測試上的應用奠定了良好的基礎。
[Abstract]:HgCdTe semiconductor material with its excellent photoelectric characteristics, since it has become an important material for the preparation of high performance infrared detector. With the rapid development of the third generation HgCdTe infrared detector technology, low cost and large-scale focal plane chip preparation process needs more stable and higher chip yield, and in space remote sensing application in space, the complex application environment is the reliability of HgCdTe photovoltaic detectors chip put forward higher requirements. Whether the process monitoring, process improvement device or chip failure analysis should be established on the basis of accurate characterization of the quality of each part of the structure of the detector chip, at the same time parameters quantitative analysis method, from the test results many batches of statistical analysis on the changing trend of the chip performance, continuous improvement of device technology, improve the reliability and stability of devices Provide an analysis method and quantitative evaluation method of effective. However, microelectronic integrated test structure generally use the physical model, the experimental data analysis method is based on the characteristics of silicon based devices, and did not consider the unique properties of HgCdTe photovoltaic devices (the forbidden bandwidth is narrow, the carrier easily degenerate). Aiming at the performance impact HgCdTe device and long-term reliability of common factors -- the surface leakage current of HgCdTe passivation layer - metal interface state and HgCdTe contact, on the gated diode, MIS capacitor and transmission line test structures, this paper presents a physical model and data analysis method, which lays the theoretical foundation for the application of these test structures in a large-scale HgCdTe infrared detector in the chip. The main research contents are as follows: 1. HgCdTe gated diode and surface leakage mechanism. This paper uses gate controlled diode structure Study on the influence of the surface potential and the dark current of HgCdTe photovoltaic devices is proposed. The theoretical model of dynamic impedance of different mechanism of surface leakage: surface area tired, with appropriate modified tunneling current model to describe the surface of the tunneling current; surface strong inversion channel is formed when using the transmission line model of surface current model the channel. By choosing the proper parameters of the surface of the flat band voltage VFB, Nst surface defect density and channel carrier mobility of C, the model can describe the wave HgCdTe diodes better merit and scale factor R0A and dark current relationship between surface potential. Experimental results show that the proposed surface leakage current model to better describe and quantitative characterization of the device surface leakage current, provide the basis for the.2. metal insulator for the further improvement of HgCdTe device technology (MIS) device capacitance theory and interface characterization According to the characteristics of HgCdTe technology. The establishment of the Poisson equation contains a non parabolic conduction band and carrier degeneracy, and use numerical method to get MIS HgCdTe devices with high frequency, the ideal C-V curve; summarizes the various influence factors of MIS devices are ideal for low and high frequency HgCdTe C-V curve; discussed the fact the minimum value of high frequency C-V curves of HgCdTe MIS devices the surface treatment technology closely related, presents a high frequency equivalent interface trap charge model to describe this phenomenon, for the extraction of the ideal high frequency C-V curves of the interface state density correction, the extraction of the interface state density and the size of the band gap in the distribution is more reasonable. The theoretical and numerical impact monitoring the analysis method is successfully applied to the performance of the same batch of MIS devices and different processes of MIS devices. The Cd Te/Zn S double layer passivation MIS device testing The physical parameters are as follows: the insulating layer insulating layer fixed charge density, trap charge density, the interface trap density in minimum zone in the high frequency equivalent characterization techniques of interface trap density of.3. nonlinear metal semiconductor contact metal semiconductor contact. Combined with current transport properties, considered the rectifying effect of current crowding effects and gold semi contact, we propose a nonlinear transmission line model; the thermal electron emission system as an example, discusses the characteristics of IV electrode to describe the nonlinear transmission line model; analysis of the current transmission length of nonlinear transmission line model and the linear model of transmission line in different current transmission length of Ltg in the new model and the current flowing, can describe the current is more reasonable on the electrode of the aggregation effect, provides guidance for design of HgCdTe focal plane chip. By using the method of nonlinear analysis of transmission line model and the corresponding data Study on electrical characteristics of Au/Sn/p-Hg Cd contact Te, the relative physical parameters were obtained: the Schottky barrier height, ideal factor n=1.45, ohmic contact resistance, resistance of semiconductor thin film electrode, the current transmission length of Ltg between 8~11 and m and Study on test methods of.4. passivation layer resistivity. Current flowing on Cd Te/Zn evaporation preparation the electron beam S passivation layer current voltage characteristic and resistivity by using MIS structure, wherein the gate electrode of the high impedance accounted for 62.5% of the total, the resistivity between. In addition, this paper simulated the potential distribution of four probe test materials using mirror image charge method, analyzes the influence of probe finite size on the measurement accuracy of simulation. The results pointed out that in the infinite thick material, the common calculation methods only greater than in the ratio of the diameter of the probe and probe spacing of 3 times to obtain accurate resistivity (relative error Less than 1%); in finite thickness materials, by introducing the approximate formula of error is much larger than the size of probe error introduced by numerical simulation, accurate analysis requires accurate calculation of the resistivity of the materials in case of need. The results of the study for the four probe method has laid a good foundation for the application of micro resistivity test on the passivation layer.

【學位授予單位】：中國科學院研究生院(上海技術物理研究所)
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TN215

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本文編號：1411111