Si(001)斜切衬底上Ge量子点的固相外延生长

研究了Si(001)面偏[110]方向6°斜切衬底上Ge量子点的固相外延生长.实验结果表明,在Si(001)6°斜切衬底上固相外延生长Ge量子点的最佳退火温度为640℃,在斜切衬底上成岛生长的临界厚度低于在Si(001)衬底成岛生长的临界厚度,6°斜切衬底上淀积0.7nm Ge即可成岛,少于Si(001)衬底片上Ge成岛所需的淀积量.从Ge量子点的密度随固相外延温度的变化曲线,得到Ge量子点的激活能为1.9eV,远高于Si(111)面上固相外延Ge量子点的激活能0.3eV.实验亦发现,在Si(001)斜切衬底上固相外延生长的Ge量子点较Si(001)衬底上形成的量子点的热稳定性要好.     

使用低温电荷灵敏前置放大器的新型Ge（Li）探测器

本文介绍了使用低温电荷灵敏放大器的Ge(Li)探测器的设计、调整及性能,它能方便地配用反符合环探测器。     

Surface Event Rejection of the EDELWEISS Cryogenic Germanium Detectors Based on NbSi Thin Film Sensors

Near-surface-events are a major limitation to the performance of cryogenic massive germanium heat and ionisation detectors for dark matter search, due to their incomplete charge collection. We present here a powerful method of surface event identification based on the transient heat signal of a Ge bolometer, equipped with two NbSi high impedance thin film sensors. Calibration runs using electrons and low energy gamma particles from a ¹⁰⁹Cd source show highly effective surface event rejection down to the heat threshold energy. Neutron and gamma source calibrations were realised to get information on the fiducial volume of the Ge absorber. First results from low background data taking are discussed.     

Self-organization of a 2D lattice on a surface of Ge single crystal after irradiation with Nd:YAG laser

Experimentally observed self-organization of a 2D lattice on the surface of Ge single crystal after irradiation by pulsed Nd:YAG laser is reported. The 2D lattice consists of nano-size hills arranged in a pattern of C_6i point group symmetry and is characterized by translational symmetry with the period of 1 μm. Calculations of time-dependent distribution of temperature in the bulk of the Ge sample are presented to explain the phenomenon. The calculations show that overheating of the crystal lattice occurs at laser radiation intensities exceeding 30 MW/cm². According to synergetic ideas, the presence of the non-equilibrium liquid phase of Ge and a huge gradient of temperature (∼3×10⁸ K/m) can lead to self-organization of the 2D lattice similar to Benard cells.     

改进的“三图法”在煤矿顶板水害评价中的应用——以东胜煤田台格庙勘查区为例

通过建立台格庙勘查区首采煤层冒裂安全性分区图和煤层顶板含水层富水性分区图,来对煤层顶板的含水层涌(突)水条件进行评价。针对勘查区煤层厚度变化大、顶板无稳定隔水层,顶板含水层富水性较弱的特点,在传统的“三图法”基础上,充分考虑了含水层的富水性和导水裂缝带发育高度这两个因素,选用导水裂缝带高度与含水层厚度的百分比来表示导水裂缝带发育高度对含水层涌(突)水的影响,在此基础上对首采煤层顶板含水层涌(突)水条件进行综合分区评价。四井田中部及二井田北部地区涌(突)水危险性为较危险区,三井田北部、五井田南部及勘查区南部局部地区涌(突)水危险性为过渡区,其他地段为安全区、较安全区。针对顶板充水含水层涌(突)水条件综合分区,提出了疏放水、注浆、监测等防治水措施建议。     

量子点红外探测器研究进展

量子点红外光电探测器(QDIP)凭借自身的优点,未来很有可能与碲镉汞(HgCdTe)红外探测器、量子阱红外光电探测器(QWIP)和非制冷微测辐射热计相竞争。目前,普遍采用自组织方法生长量子点,研究主要集中在:①隧道量子点红外探测器(T-QDIP);②量子阱中量子点(DWELL)红外探测器;③Si基QDIP;④Ge QDIP。本文阐述正在研究的几种QDIP,并对下一代传感器用QDIP进行预测。     

Theoretical modeling of the interface recombination effect on the performance of Ⅲ-Ⅴtandem solar cells

A typical GaInP/GaInAs/Ge tandem solar cell structure operating under AM0 illumination is proposed, and the current-voltage curves are calculated for different recombination velocities at both front and back-surfaces of the three subcells by using a theoretical model including optical and electrical modules. It is found that the surface recombination at the top GaInP cell is the main limitation for obtaining high efficiency tandem solar cells.     

Electrical characteristics of Ge MOS device on Si substrate with thermal SiON as gate dielectric

Metal-oxide-semiconductor (MOS) devices, using a Si substrate and a thermal SiON film as the gate dielectric on a Ge layer, have been physically and electrically characterized. The small frequency dispersion and negligible hysteresis demonstrate very few oxide traps. The efficiency of Ge surface passivation is evidenced by the acceptable interface trap density of 7.08 × 10¹¹ cm⁻² eV⁻¹ close to midgap, which is critical for the enhancement of the carrier mobility in MOSFET devices. On the other hand, for the thermal SiON film, a higher permittivity of 4.86 can be achieved by NH₃ nitridation and a subsequent N₂O treatment of an as-grown SiO₂ film without compromising its leakage current. The conduction mechanism is confirmed to be Fowler-Nordheim (F-N) tunneling with extracted electron barrier height of 2.71 eV. Combining with these promising properties, the SiON film shows a great potential to further boost the performance of Ge MOSFETs. Most importantly, without using a Ge substrate, the SiON film on a Ge layer can be formed by the process fully compatible with incumbent ultra-large-scale integration (ULSI) technology, and hence, providing an economic way of fabricating high-performance Ge MOSFETs.     

超结硅锗功率二极管电学特性的研究

超结SiGe功率开关二极管可以克服常规Si功率二极管存在的一些缺陷,如阻断电压增大的同时,正向导通压降也将增大,反向恢复时间也变长。该新型功率二极管有两个重要特点:一是由轻掺杂的p型柱和n型柱相互交替形成超结结构,代替传统功率二极管的n-基区;二是p+区采用很薄的应变SiGe材料。该器件可以同时实现高阻断电压、低正向压降和快速恢复的电学特性。与相同器件厚度的常规Si功率二极管相比较,反向阻断电压提高了42%,反向恢复时间缩短了40%,正向压降减小了约0.1V(正向电流密度为100A/cm2时)。应变SiGe层中Ge含量和器件的基区厚度是影响超结SiGe二极管电学特性的重要参数,详细分析了该材料参数和结构参数对正向导通特性、反向阻断特性和反向恢复特性的影响,为器件结构设计提供了实用的参考价值。     

HfO_2/TaON叠层栅介质Ge pMOSFET制备及迁移率退化研究

为提高high-k/Ge界面质量,在high-k介质和Ge表面引入薄的TaON界面层。相对于没有界面层的样品,HfO2/TaON叠层栅介质Ge pMOSFET样品的空穴迁移率有显著提高,但仍小于理论预测值。利用high-k栅介质MOSFET中各种新的附加散射机制,分析了迁移率退化的原因,模型计算结果与实验结果一致。