排序方式: 共有74条查询结果,搜索用时 15 毫秒
61.
Nanoelectronic devices---resonant tunnelling diodes grown on InP substrates by molecular beam epitaxy with peak to valley current ratio of 17 at room temperature 下载免费PDF全文
This paper reports that InAs/In$_{0.53}$Ga$_{0.47}$As/AlAs resonant tunnelling diodes have
been grown on InP substrates by molecular beam epitaxy. Peak to valley
current ratio of these devices is 17 at 300K. A peak current density of
3kA/cm$^{2}$ has been obtained for diodes with AlAs barriers of ten
monolayers, and an In$_{0.53}$Ga$_{0.47}$As well of eight monolayers with
four monolayers of InAs insert layer. The effects of growth interruption for
smoothing potential barrier interfaces have been investigated by high
resolution transmission electron microscope. 相似文献
62.
63.
64.
在兰州充气谱仪上,设计安装了一套新的焦平面探测系统,该系统包括飞行时间(TOF) 探测器、盒型硅(Si-box) 探测器阵列和反符合(Veto) 探测器3 部分。Si-box 探测器阵列是由3 块位置灵敏硅探测器(PSSD) 和8 块周边硅探测器(SSD) 构成,它对注入核的 衰变的探测效率达到80% 左右。Si-box 探测器阵列与TOF 探测器关联可以有效区分注入信号和 衰变信号。Veto 探测器与Si-box 探测器阵列和TOF 探测器关联可以反符合掉高能轻粒子对注入信号和 衰变信号的干扰。简要介绍了PSSD 的能量和位置刻度方法。这套探测器系统已经应用于40Ca+175Lu 和40Ca+169Tm 的实验。实验结果表明,该探测器系统具备很好的本底抑制能力,能够给出干净的a衰变能谱,结合能量-时间-位置关联测量方法可以实现对单原子的探测和鉴别,总体上达到了预期的设计要求。A new designed focal plane detection system was mounted at the gas-filled recoil separator at Institute of Modern Physics, Chinese Academy of Sciences, which consisted of a time-of-flight (TOF) detector, a silicon-box (Sibox) detector array and a silicon veto detector. Three position sensitive silicon detectors (PSSD) were surrounded by eight side silicon detectors (SSD) without position sensitive, forming a box of the detector open from the front side. The detection efficiency for -decays of implanted nuclei was about 80%. The anticoincidence condition for the signals from the TOF detector and Si-box detector array was used to distinguish between the pulses originating from the implanted nuclei and their -decays. The veto detector information was used to discriminate events due to high-energy charged particles.External energy calibration and position calibration of PSSD are described concisely in this work. This systemhas been used in experiments of 40Ca+175Lu and 40Ca+169Tm. Clean a-decay spectra obtained in these reactions indicated the detection system has a good performance in background suppression. Evaporation residues can be identified by the energy-time-position correlation method. On the whole, the new designed focal plane detection system has achieved thedesign requirements. 相似文献
65.
We report a resonant tunnelling diode (RTD) small signal equivalent circuit model consisting of quantum capacitance and quantum inductance. The model is verified through the actual InAs/In0.53Ga0.47As/AlAs RTD fabricated on an InP substrate. Model parameters are extracted by fitting the equivalent circuit model with ac measurement data in three different regions of RTD current-voltage (I-V) characteristics. The electron lifetime, representing the average time that the carriers remain in the quasibound states during the tunnelling process, is also calculated to be 2.09ps. 相似文献
66.
利用能量为170MeV的35Cl束流,通过157Gd(35Cl,4n)熔合蒸发反应研究了188Tl的高自旋态能级结构.依据实验结果建立了188Tl基于πh9/2(○×)νi13/2组态的转动带.根据双奇Tl核能级结构的相似性,指定了188Tlπh9/2(○×)νi13/2扁椭球转动带的自旋值.结果表明在188Tl中,πh9/2(○×)νi13/2扁椭球转动带在低自旋区具有旋称反转性质.利用包含了质子-中子剩余相互作用的准粒子-转子模型,定性地解释了πh9/2(○×)νi13/2扁椭球转动带的低自旋区旋称反转现象. 相似文献
67.
充气反冲核谱仪(SHANS)是目前国内合成缺中子锕系新核素、研究重核素α衰变性质的重要实验装置。为进一步提高焦平面探测阵列对重核素α衰变粒子和射线的探测效率,计划对现有探测装置进行升级。本文的主要工作是采用基于蒙特卡罗方法的GEANT4软件对现有的谱仪探测器阵列进行模拟,并与实验测量数据进行比较,以验证程序的准确性。结果表明,新探测系统对α衰变粒子的探测效率可达到88%左右,对能量在1 MeV的$\gamma$ 射线全能峰的探测效率约为7%。 相似文献
68.
69.
张玉虎郭松 周小红马龙 Oshima M. Toh Y. Koizumi M. Osa A. Kimura A. Hatsukawa Y. Sugawara M. Kusakari H. 《中国物理快报》2005,22(11):2788-2791
High spin states in ^174Re have been investigated via the ^152Sm (^27 Al, 5nγ) ^174Re reaction. Gamma-ray excitation functions, x-γ and γ-γ coincidences have been measured. Two rotational bands built on the πh9/2 × vi13/2 and πh11/2 × vi13/2 configurations have been identified and extended up to high-spin states. The relative spin and parity of the band levels have been unambiguously fixed due to observations of several inter-band transitions. Both the bands show the low-spin signature inversion, which is consistent with systematic expectations for the high-j two-quasiparticle bands in the A = 170 mass region. 相似文献
70.