层叠结构的Si0.65Ge0.35/Si红外探测器的微结构研究

采用定位的横断面透射电子显微术观察Ｐ＾＋－Ｓｉ０．６５Ｇｅ０．３５／ｐ－Ｓｉ异质结内光发射红外探测器的微结构。该器件光敏区由６层Ｐ＋－Ｓｉ０．６５Ｇｅ０．３６和５层ＵＤ－Ｓｉ层组成,每层都比较平整,各层厚度分别为６ｎｍ和３２ｎｍ,在Ｓｉ０．６５Ｇｅ０．３５／ＵＤ－Ｓｉ界面处存在应力场,但未到晶体缺陷,非晶ＳｉＯ２台阶上的Ｓｉ０．６５Ｇｅ０．３５和ＵＤ－Ｓｉ层是波浪状的多晶层,光敏区的边界处存在小于     

红外探测器微结构的HREM观察

采用定位横断面制样的高分辨电子显微技术（ＨＲＥＭ）观察了Ｐ＋－Ｓｉ０．６５Ｇｅ０．３５／Ｐ－Ｓｉ异质结内光发射红外探测器的微结构．该器件光敏区是由３层Ｐ＋－Ｓｉ０．６５Ｇｅ０．３５和２层ＵＤ－Ｓｉ（未掺杂硅）组成,Ｓｉ０．６５Ｇｅ０．３５／ＵＤ－Ｓｉ层间界面不明锐,有一个由于Ｇｅ原子不均匀扩散造成的过渡带．这个过渡带缓和了界面的失配应力,因而未观察到界面晶体缺陷和严重的晶格畸变．在光敏区边缘有呈倒三角形的缺陷区,缺陷的主要类型为层错和微孪晶．层错在（１　１１）面上,而微孪晶的厚度约为２～４晶面间距,其孪晶     

红外探测器

本文简要介绍了多量子阱探测器、热电探测器、混合型及单片型图象传感器等红外探测器的研究近况,并对关键技术进行评述。     

GexSi1—x／Si超晶格红外探测器最佳结构

通过对ＧｅｘＳｉ１－ｘ／Ｓｉ超晶格机理的研究，算出了ＧｅｘＳｉ１－ｘ／Ｓｉ超晶格红外探测器的最佳结构参数，以对１．３μｍ红外光有最大的利用率。     

GexSi1—x／Si异质结长波长红外探测器

描述了 Ge_xSi_(1-x)/Si 异质结长波长红外探测器的基本工作原理及结构,并结合器件介绍了实现异质结生长的各种工艺,如 MBE,CVD 等。     

GeSi／Si异质结红外探测器结构参数设计

文章对分子束外延的GeSi／Si异质结红外探测器关键参数进行了分析研究,采用经典理论对器件结构参数进行了计算,结果与实验数据吻合。     

Oxidation characteristics of Si0.85Ge0.15 nanowires

Oxidation characteristics of Si_0.85Ge_0.15 nanowires were investigated using transmission electron microscopy (TEM) analyses. Si_0.85Ge_0.15 nanowires were grown in a tube furnace by vapor–liquid–solid (VLS) method and thermally oxidized at 925 °C for 1–8 h. After oxidation, oxide thicknesses were measured using TEM images. Si_0.85Ge_0.15 nanowires showed a thicker oxide than Si nanowires, for the whole range of oxidation time. The oxidation rate of Si_0.85Ge_0.15 nanowires significantly decreased in nanowires with diameters less than 150 nm. Long-term oxidation in Si_0.85Ge_0.15 nanowire resulted in the oxidation of germanium atoms.     

Double-dopedIn0.35Al0.65As/In0.35Ga0.65As power heterojunction FET on GaAs substrate with 1 W outputpower

A double-doped metamorphic In_0.35Al_0.65As/In _0.35Ga_0.65As power heterojunction FET (HJFET) on GaAs substrate is demonstrated. The HJFET exhibits good dc characteristics, with gate forward turn on voltage of 1.0 V, breakdown voltage of 20 V, and maximum drain current of 490 mA/mm. Under RF operation at a frequency of 950 MHz, a power added efficiency of 63% with associated output power of 31.7 dBm is obtained at a gate width of 12.8 mm. This large gate width and state-of-the-art power performance in metamorphic HJFETS were enabled by a selective etching, sputtered WSi gate process and low surface roughness due to an Al_0.60Ga_0.40As_0.69Sb_0.31 strain relief buffer     

Evaluating nanotribological behavior of annealing Si0.8Ge0.2/Si films

In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load.Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration.     

Optical properties of Si0.8Ge0.2/Si multiple quantum wells

The optical property was studied on the Si_0.8Ge_0.2/Si strained multiple quantum well (MQW) structure grown using ultra-high vacuum chemical vapor deposition (UHV-CVD). Three peaks are observed in Raman spectrum, which are located at about 510, 410, and 300 cm⁻¹, corresponding to the vibration of Si–Si, Si–Ge, and Ge–Ge phonons, respectively. The photoluminescence (PL) spectrum originates from the radiative recombinations both from the Si substrate and the Si_0.8Ge_0.2/Si MQW. For Si_0.8Ge_0.2/Si strained MQW, the transition peaks related to the MQW region observed in the photocurrent (PC) spectrum were preliminarily assigned to electron–heavy hole (e–hh) and electron–light hole (e–lh) fundamental excitonic transitions.     

PtSi／p－Si肖特基势垒红外探测器的研制

介绍了ＰｔＳｉ／ｐ－Ｓｉ肖特基势垒红外探测器（简称ＩＲ－ＳＢＤ）的优化结构及探测机理，给出了探测器的光增益模型，并对器件进行了制作及性能测试。器件在７７Ｋ下，反偏４Ｖ时的反向漏电流为５×１０（－６）μＡ，对１．５２μｍ红外光的灵敏度为２．６９×１０（－２）Ａ／Ｗ，量子效率为２．４％。     

PtSi／p－Si肖特基势垒红外探测器的研制

介绍了ＰｔＳｉ／ｐ－Ｓｉ肖特基势垒红外探测器（简称ＩＲ－ＳＢＤ）的优化结构及探测机理，给出了探测器的光增益模型，并对器件进行了制作及性能测试。器件在７７Ｋ下，反偏４Ｖ时的反向漏电流为５×１０（－６）μＡ，对１．５２μｍ红外光的灵敏度为２．６９×１０（－２）Ａ／Ｗ，量子效率为２．４％。     

Microstructure and electrical characteristics of Ba0.65Sr0.35TiO3 thin films etched in CF4/Ar/O2 plasma

Radio frequency magnetron sputtered Ba_0.65Sr_0.35TiO₃ (BST) thin films were etched in CF₄/Ar/O₂ plasma by magnetically enhanced reactive ion etching technique. The etching characteristics of BST films were characterized in terms of microstructure and electrical properties. Atomic force microscopy and X-ray diffraction results indicate that the microstructure of the etched BST film is degraded because of the rugged surface and lowered intensities of BST (1 0 0), (1 1 0), (1 1 1) and (2 0 0) peaks compared to the unetched counterparts. Dielectric constant and dielectric dissipation of the unetched, etched and postannealed-after-etched BST film capacitors are 419, 346, 371, 0.018, 0.039 and 0.031 at 100 kHz, respectively. The corresponding dielectric tunability, figure of merit and remnant polarization are 19.57%, 11.56%, 17.25%, 10.87, 2.96, 5.56, 3.62 μC/cm², 2.32 and 2.81 μC/cm² at 25 V, respectively. The leakage current density of 1.75 × 10⁻⁴ A/cm² at 15 V for the etched BST capacitor is over two orders of magnitude higher than 1.28 × 10⁻⁶ A/cm² for the unetched capacitor, while leakage current density of the postannealed-after-etched capacitor decreases slightly. It means that the electrical properties of the etched BST film are deteriorated due to the CF₄/Ar/O₂ plasma-induced damage. Furthermore, the damage is alleviated, and the degraded microstructure and electrical properties are partially recovered after the etched BST film is postannealed at 923 K for 20 min under a flowing O₂ ambience.     

Investigation of Coulomb scattering on sSi/Si0.5Ge0.5/sSOI quantum-well p-MOSFETs

sSi/Si_0.5Ge_0.5/sSOI quantum-well (QW) p-MOSFETs with HfO₂/TiN gate stack were fabricated and characterized. According to the low temperature experimental results, carrier mobility of the strained Si_0.5Ge_0.5 QW p-MOSFET was mainly governed by phonon scattering from 300 to 150 K and Coulomb scattering below 150 K, respectively. Coulomb scattering was intensified by the accumulated inversion charges in the Si cap layer of this Si/SiGe heterostructure, which led to a degradation of carrier mobility in the SiGe channel, especially at low temperature.     

Gate oxide integrity of thermal oxide grown on high temperatureformed Si0.3Ge0.7

We have investigated the gate oxide integrity of thermal oxides direct grown on high temperature formed Si_0.3Ge_0.7. Good oxide integrity is evidenced by the low interface-trap density of 5.9×10¹⁰ eV^-1 cm^-2, low oxide charge density of -5.6×10¹⁰ cm^-2, and the small stress-induced leakage current after -3.3 V stress for 10 000 s. The good gate oxide integrity is due to the high temperature formed and strain-relaxed Si_0.3Ge_0.7 that has a original smooth surface and stable after subsequent high temperature process     

Quantized conductance in a Si/Si0.7Ge0.3 split-gate device and impurity-related magnetotransport phenomena

We have defined a quantum point-contact by the split-gate technique in a Si/SiGe heterostructure containing a two-dimensional electron gas with an elastic mean free path of about 1.3 μm. The conductance of this device shows typical steps very close to multiples of 4e² h⁻¹. Upon application of a perpendicular magnetic field the spin and valley degeneracies are lifted and magnetic depopulation of the one-dimensional subbands can be observed. The appearance of Aharonov-Bohm oscillations for B ≥ 2T and of resonant tunneling peaks close to “pinch-off” indicates the presence of impurities close to the constriction.