高纯锗中浅受主的光热电离光谱

在液氦温度附近, 运用傅里叶变换光谱以及与之相连的磁光光谱系统, 对室温电阻率约为50Ω·cm的p型高纯锗样品进行了高灵敏度的光热电离光谱的研究.从实验上确定了高纯锗样品中浅杂质光热电离的最佳温度范围, 在该温度范围内测量了样品的光热电离光谱, 指出该样品中主要杂质为浅受主硼与铝. 对杂质谱线发生分裂的两种原因, 补偿性杂质导致的快速复合以及随机应力等, 进行了分析讨论.     

高纯硅中补偿性杂质的光热电离光谱

首先测量了高纯n型硅样品在接近液氦温度区域内随温度变化的光热电离光谱,确定了硅样品的最佳光热电离温度范围. 在该温度范围内,在有本征带隙光照射条件下,测量了样品的高分辨率光热电离光谱,同时观察到了来自主要浅杂质施主磷以及补偿性杂质硼的正信号. 随后,应用外加磁场,对硼的光热电离光谱进行了研究,发现来自硼的光热电离信号,在外加磁场作用下,发生了由正向负信号的转变. 通过对该现象进行分析讨论,排除了该现象是温度效应的可能,指出普遍用来解释补偿性杂质光热电离响应的Darken模型存在不足,而少数载流子快速复合模 关键词： 高纯硅 光热电离光谱 元素半导体中的杂质和缺陷能级 少数载流子快速复合     

高纯硅中补偿性杂质的光热电离光谱

首先测量了高纯n型硅样品在接近液氦温度区域内随温度变化的光热电离光谱，确定了硅样品的最佳光热电离温度范围. 在该温度范围内，在有本征带隙光照射条件下，测量了样品的高分辨率光热电离光谱，同时观察到了来自主要浅杂质施主磷以及补偿性杂质硼的正信号. 随后，应用外加磁场，对硼的光热电离光谱进行了研究，发现来自硼的光热电离信号，在外加磁场作用下，发生了由正向负信号的转变. 通过对该现象进行分析讨论，排除了该现象是温度效应的可能，指出普遍用来解释补偿性杂质光热电离响应的Darken模型存在不足，而少数载流子快速复合模     

半导体中浅杂质的傅里叶变换光热电离光谱

本文报道与快扫描傅里叶变换红外光谱仪相结合的光热电离光谱实验装置和测量系统。采用该系统高分辨率、高灵敏度地研究和测量高纯锗和高纯硅中的剩余浅杂质获得成功。在P型超纯Ge中发现浓度低达10⁸cm^-3的硼受主杂质的光热电离谱线,而探测灵敏度则至少可达10⁷cm^-3;在n型高纯Si中观测到Li-O复合型浅施主中心D(Li,O);施加本征激发光后在P型高纯Si中同时观察到B受主和P施主的跃迁谱线系。此外,在Si,Ge中均观察到 关键词：     

ZnSe:Al发光光谱的研究

本文用热扩散的方法在Zn饱和蒸气压下,把Al掺杂到高纯ZnSe单晶中,通过77K下的光致发光光谱研究了Al杂质的发光行为,讨论了施主一受主对发射强度、自激活中心发射强度随掺杂温度的变化规律以及与Zn饱和蒸气压的关系.本文首次报道了在300℃～900℃温度范围内进行Al掺杂的ZnSe的发光规律.     

发射光谱测定微量稀土杂质用的一种新的载体KBH4的研究

介绍了高纯稀土氧化物中微量稀土杂质的光谱测定方法，本工作用碳粉做缓冲剂，ＫＢＨ４做载体，用化学方法将大量稀土分离掉，而后对余下微量和稀土杂质进行光谱测定。只要取样量不少于１克，则可测定的纯度为９９．９９９９５％的稀土样品。     

井型高纯锗探测器体源样品无源效率刻度

采用蒙特卡罗程序MCNP建立物理模型,对井型高纯锗探测器的效率进行虚拟刻度。模拟计算在密度为0.4,1.2 gcm-3的6种不同成分环境样品中,探测器对射线的探测效率,当能量高于0.10 MeV时,体源样品的探测效率主要与样品密度、射线能量相关。以土壤、水和植物油样品为代表,结合所选取的函数模型,确定了密度范围0.1~1.6 gcm-3的固体源、密度1.0 gcm-3的水溶液和密度0.92 gcm-3的油溶液体源的效率函数及参数。实验采用标准源,对探测效率模拟结果进行了验证,探测效率的模拟值与实验值符合较好,二者误差均在3%以内。说明MCNP程序可以较为准确地模拟计算井型高纯锗探测器对射线的探测效率,验证了该无源效率刻度方法的准确性和可行性。     

应变Si1-xGex层中p型杂质电离常温和低温特性

本文采用解析的方法计算了应变Si1-xGex层中p型杂质电离度与Ge组分x、温度T以及掺杂浓度N的关系.发现常温时,在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度的先变小,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加先变大,而后几乎不变;重掺杂时,杂质电离能变为0后,杂质电离度为1.低温下,轻掺杂时,载流子低温冻析效应较为明显,杂质的电离度普遍较小,当掺杂浓度大于Mott转换点时,载流子冻析效应不再明显,电离率迅速上升到1.在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度先变小,后变大,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加变大;重掺杂时,杂质电离能变为0后,杂质电离度为1.     

激光剥蚀-电感耦合等离子体质谱法测定高纯铪中10种杂质元素

高纯铪由于具有独特的理化性质,在核反应堆、等离子切割机、光学元件等方面有着重要的应用。高纯铪中杂质的种类和含量会影响高纯铪的物理化学性能,应用中对高纯铪纯度的要求也越来越高,这就对高纯铪的分析检测技术提出了更高的要求。激光剥蚀-电感耦合等离子体质谱法（LA-ICP-MS）是激光剥蚀进样技术与电感耦合等离子体质谱联用,可以直接分析固体样品,并且方法前处理简单,可以避免样品前处理过程中引入杂质,是一项高效、快速、精密的分析技术,在环境、地质、冶金、燃料能源、材料、生物医药、考古等领域广泛应用。所以,激光剥蚀-电感耦合等离子体质谱法（LA-ICP-MS）是高纯金属杂质元素最佳检测方法之一。还未见有应用LA-ICP-MS于高纯铪样品的报道。用LA-ICP-MS对高纯铪中10种杂质元素（Al,Sc,Ti,Fe,Ni,Cu,Mo,Ag,Sn,W）进行定量分析。为了降低激光剥蚀过程中元素的分馏效应,提高信号灵敏度和稳定度,对激光剥蚀参数进行优化实验。确定了激光剥蚀的最优仪器参数为：氦气流量600 mL·min-1,激光能量90%,剥蚀孔径150 μm,激光扫描速度60 μm·s-1,激光脉冲频率20 Hz。经实验优化后的ICP-MS仪器工作参数为：RF功率1 450 W,射频匹配电压1.8 V,载气流量0.85 L·min-1,冷却器流量0.85 L·min-1,采样深度7.5 mm。在最优参数条件下,利用内控标样建立工作曲线,各杂质元素标准曲线的线性相关系数为0.993 6～0.999 8。采集载气空白的信号强度,平行测定11次,以3倍空白信号的标准偏差所对应的含量作为元素的检出限,得到各元素的检出限为0.001~0.08 μg·g-1。将高纯铪制成尺寸合适的样品,用硝酸洗去样品表面的氧化物,将其装入剥蚀池中,运用线扫描剥蚀方式,在最佳仪器工作条件下,对三个高纯铪样品中的10种杂质元素进行定量分析。实验结果显示,杂质元素含量为0.17～36.76 μg·g-1,相对标准偏差为1.4%～20%,精密度良好。以184W为例,将LA-ICP-MS法和ICP-MS法的测定结果进行t检验,三个样品的t值分别为2.14,1.64和2.11,均小于显著性水平为0.05时的临界值（t_{0.05, 12}=2.18）,说明LA-ICP-MS法和ICP-MS法的测定结果在置信度为95%时没有显著性差异,即正确度良好。所以,该方法正确度和精密度良好,可用于高纯铪中杂质的定量分析。     

近红外光谱分析中温度影响的修正

样品温度变化会对模型预测结果产生影响,为解决这个问题,首先,对同一样品不同温度下的光谱与同一样品相同温度的光谱进行了比较。结果显示,不同温度下的光谱差异较大。然后研究了样品温度对玉米粗蛋白模型的预测结果的影响,对随机选取的粗蛋白含量为6.04%的样品不同温度采集光谱,对这些光谱进行预处理消除温度之外的因素对光谱的影响,将预处理后的光谱代入已建立好的模型中进行预测,结果显示,预测结果与实测值之间的差别随着光谱温度与建模温度相之间差别的增大而增大,最大的误差为1.12%。为了解决温度对模型预测结果的影响,进而分析了温度与不同温度下的光谱数据之间的关系,发现在去除了光谱两端噪声较严重的区域后,不同温度下,同一波长点处的光谱数据之间存在一定的线性关系。依据这一发现,文中提出了温度修正理论,以建模时的光谱为基准光谱,然后根据温度与光谱之间的线性关系使用线性回归算法对不同波长点的光谱进行一元线性回归,求出不同温度下的光谱与基准光谱之间的差,最后将不同温度下的光谱校正为基准光谱,通过该理论对光谱进行校正之后,不同温度下的同一样品的光谱之间的差别和修正之前相比已经有了很大改善,将修正后的光谱代入模型,大部分预测结果得到了提高,符合国家标准±0.5%以下的要求。最后使用和建模无关的34个不同含量的样品对该温度修正理论进行验证,光谱修正前后粗蛋白的模型预测值与标准理化值决定系数分别为0.910和0.982,均方根误差分别为0.558和0.172,平均相对误差分别为6.05%和1.75%。该温度修正理论从近红外光谱分析的本质上进行了温度修正,为其他样品的温度修正提供了参考,有利于手持式近红外光谱仪使用的推广。     

A PTIS study of quenched-in acceptors in germanium

The shallow acceptors produced in germanium crystals by quenching from 820–925 C have been studied for the first time using Photo-Thermal Ionization Spectroscopy (PTIS). We have found two acceptor-continua, which correspond to the E_v + 8.4 meV and E_v + 12 meV levels observed in earlier Hall measurements. With the lower energy continuum there are associated two previously unobserved hydrogenic acceptors. They are shallower than any known acceptor in germanium: their ionization energies are 8.69 ±0.01 meV and 9.48 ±0.01 meV. We attribute the acceptors to two different defects because of differences in their creation and annealing behaviour. No discrete lines were found to be associated with the higher energy continuum. We estimate the acceptor ionization energy to be about 14 meV. Finally, we have observed a number of as yet unexplained negative lines superimposed on both acceptor-continua.     

Electronic properties of hydrogen-related complexes in pure semiconductors

Hydrogen has been shown to activate the neutral impurities carbon, silicon and oxygen in ultra-pure germanium and form shallow level complexes. The double acceptors beryllium and zinc in silicon and germanium, as well as the triple acceptor copper in germanium, can be partially passivated, leading to single hole acceptors. The study of the electronic level spectrum of the single carrier bound to these centers at low temperatures has provided much information on symmetry and composition. Most centers reveal a symmetry axis along [1 1 1] and are static. In some cases hydrogen has been found to tunnel between equivalent real space positions. hoto hermal onization pectroscopy (PTIS) has been the most important tool for the study of the optical transitions of the hole (electron) in these hydrogen containing complexes. This photoconductivity technique combines high sensitivity with high resolution and permits the study of shallow acceptors or donors present at concentrations as low as 10⁸ cm^-3. Even lower limits may be attained under favorable circumstances.     

Long Lifetime State of Shallow Donor Centres for Silicon Based THz Sources

Impurity centres in high purity silicon with ionization energies 38.32 and 40.09meV are observed by photothermal ionization spectroscopy measurements. Their typical shallow donor characteristics are approved by good agreement with theoretic evaluation under varying magnetic fields. The 2p0 state lifetime of one donor centres are more than 3 times longer than that of phosphorus in the same silicon sample. Compared to phosphorus which has been already successfully exploited to produce silicon-based THz radiations, this shallow donor centre has a pronounced enhancement on lifetime and quality factor of population inversion level. Hence, silicon with this donor centre would be a potential excellent candidate to develop improved silicon-based THz sources.     

Preparation of hydrogenated amorphous germanium by reactive thermal evaporation

Hydrogenated amorphous germanium was prepared by the thermal evaporation of high purity polycrystalline germanium in an atmosphere of hydrogen plasma produced by high voltage AC discharge of molecular hydrogen. The addition of hydrogen during the thermal evaporation of germanium is shown to improve the electrical properties of the resulting amorphous germanium films considerably by saturation of dangling bonds, if the dissociation of molecular hydrogen takes place. Hydrogenated sample deposited at 200°C has shown a high resistivity and an activation type conduction (with an activation energy of 0.38–0.39 eV) in measuring temperature range (above room temperature).     

Far-infrared photoconductivity spectra of quenched-in acceptors in Germanium: absorption and photo-thermal ionization lines of two new shallow acceptors

The far-infrared photoconductivity spectra of germanium crystals quenched from T>800C show three new sets of hydrogenic acceptor excitation lines, in addition to the 8.69 meV (SA^'₁) and 9.48 meV (SA^“₁) acceptor series reported earlier. The corresponding ground state binding energies are 13.89 meV (SA^'₂), 14.42 meV (SA^“₂), and 17.89 meV (SA₃). We tentatively attribute both the SA^'₂ and the SA^“₂ line series to one acceptor complex with a multiple ground state. At high acceptor concentrations the excitation lines are seen as sharp minima superimposed on a continuous photoconductivity background. With decreasing acceptor concentration, or increasing temperature, they gradually evolve into the familiar positive-going photo-thermal ionization peaks. This is explained by the different concentration and temperature dependence of the cross-sections for the absorption and photo-thermal ionization mechanisms.     

Sum rule for the intraband absorption and the oscillator strengths of the optical transitions in the shallow acceptor impurities in germanium

The sum rule for the cross-section of intraband optical absorption is derived in the effective-mass approximation. A numerical method of calculation of the wave functions of the shallow acceptors in the spherical approximation is developed. The oscillator strengths of several lines in the spectra of the group III impurities in germanium are determined.     

Polarization of the terahertz radiation of uniaxially compressed p germanium at the electrical breakdown of a shallow acceptor impurity

The spectral and polarization investigations of spontaneous terahertz radiation under the conditions of the electrical breakdown of shallow acceptors (gallium) in germanium crystals have been reported. The radiation spectra of crystals uniaxially compressed in the [111] direction at a pressure of about 3 kbar, as well as undeformed crystals, have been measured at T = 5 K using a Fourier spectrometer with step scanning. The polarization of radiation has been estimated for transitions of holes between various states of a shallow acceptor in uniaxially compressed germanium. To identify the observed radiation lines, their experimental energies and polarizations have been compared to the respective calculated values. The spectral lines corresponding to the transitions of holes from the resonance state to the excited states of acceptors have been identified.