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.     

高T_c超导体YBa_2Cu_3O_(9-δ)的远红外反射光谱

测量了高T_c超导体YBa_2Cu_3O_(9-δ)(T_c=90K)的远红外反射光谱,温度变化范围为4.2—200K。在30—360cm_(-1)光谱区间内出现了六个结构:S_1,S_2,N_1,N_2,N_3和N_4。S_1和S_2仅在超导态中出现,而其他四个结构在超导态和正常态中都存在。我们将s_1和S_2与超导能隙联系起来,认为N_i(i=(1—4))是材料的横光学声子反射带     

高压下半磁半导体Cd1-xMnxSe的相变研究

利用金刚石对顶砧高压装置,并分别用光吸收和X射线衍射实验方法测量了Cd_1-xMn_xSe样品在高压下的相变,发现该样品的高压相变是不可逆,常压下Cd_1-xMn_xSe具有纤维锌矿结构,高压下变为NaCl结构,而卸压后成为闪锌矿结构,同时给出了Cd_1-xMn_xSe样品的相变压力及其与组分x的关系。 关键词：     

液相外延GaAs_（1-x）_P_x_混晶的光学声子，等离子体激元和LO声子-等离子激元耦合模

在40--7 0 0 (1/cm)波数和4.2--300 K 温度范围内研究了不同组份液相外延n 型GaAs_（1-x）_P_x__样品的红外反射谱. 对反射谱进行了鹰谐振子拟合与K-K 关系计算.从而获得了有关描述GaAs_（1-x）_P_x__样品的光学声子模、等离子体激元、LO 声子-等离子体激元藕合模的重要物理参量及红外光学常数信息. 基于这些计算结果, 提出了双导带谷并计及与x 能谷相联系的施主能级模型, 用它解释等离子体激元频率和实验观察的三支主要的祸合模的温度变化规律。 关键词：     

液相外延GaAs_(1-x)P_x混晶的光学声子、等离子体激元和LO声子-等离子体激元耦合模

在40—700cm~(-1)波数和4.2—300K温度范围内研究了不同组份液相外延n型CaAs_(1-x)P_x样品的红外反射谱。对反射谱进行了赝谐振子拟合与K-K关系计算。从而获得了有关描述CaAs_(1-x)P_x样品的光学声子模、等离子体激元、LO声子-等离子体激元耦合模的重要物理参量及红外光学常数信息。基于这些计算结果,提出了双导带谷并计及与X能谷相联系的施主能级模型,用它解释等离子体激元频率和实验观察的三支主要的耦合模的温度变化规律。     

外延Si1-xGex薄层中浅杂质的光热电离光谱

在Si_1-xGe_x合金外延层中利用光热电离光谱方法观察到了Si_0.92Ge_0.08合金中浅施主磷的2p_±及3p_±态的分立谱线，并根据有效质量近似理论估算了Si_0.92Ge_0.08合金中磷施主的电离能为45.51meV．与硅相比，由于合金的无序效应，Si_1-xGe_x合金的分立谱线发生明显展宽 关键词：     

STRUCTURE STUDY OF MODULATION-DOPED Cd1-xMnxTe: In/CdTe STRAINED LAYER MULTIPLE QUANTUM WELLS

The photomodulated reflectivity (PR) spectroscopy of modulation-doped diluted mag-netic semiconductor Cd_1-xMn_xTe: In/CdTe multiple quantum wells has been measured at 20-300K. Several spectral features associated with intersubband transitions have been found. The band structure of Cd_1-xMn_xTe: In/CdTe has been calculated by the Hartree self-consistent method. The results show that the theory is in agreement with experiments. In addition, an abnormal transition intensity ratio of 22H (the second heavy hole subband to the second electroa subband) to 11H (the first heavy hole subband to the first electron subband) caused by electron filled effect has been reported. At low temperature, a feature associated with Fermi level is observed, which has not been reported before.     

Cd1-xMnxTe混晶的远红外吸收光谱

本文报道4.2—300K和20—400cm^-1范围内不同组份的Cd_1-xMn_xTe混晶远红外声子吸收光谱的研究结果。实验分辨了类CdTe,类MnTe剩余射线带及其TO-LO分裂,首次观察到位于混晶剩余射线吸收区内侧的低频吸收带、低x值情况下的准定域模吸收峰及其两侧的诸双声子吸收带。用缺陷晶格动力学理论估计了准定域模的出现及位置,讨论了其他吸收带的物理起源和判定。 关键词：     

导电聚合物P3MT的综合光谱研究

本文通过电调制反射谱(ER)、光调制反射谱(PR)、荧光光谱(PL)以及吸收光谱首次对导电聚合物聚三甲基噻吩(P3MT)进行综合光谱测量,并根据准一维导电体系的元激发态理论模型对实验结果作了分析,研究结果表明,导电聚合物P3MT的禁带宽度约为2eV,在70—300K的温度范围内对温度不敏感;掺杂和光照皆可诱导产生本征元激发态双极化子;离化杂质对双极化子有“钉扎效应”;光照可产生显著的激子态,本文还就P3MT中光电子交换微观过程的物理图象作了讨论。     

半导体中定域模,准定域模晶格振动的光谱研究

本文讨论了用光学方法研究杂质诱发定域化振动模的理论模型,分门别类地论述了半导体中杂质诱发的定域模、禁带模、共振模和准定域模晶格振动及非晶态半导体的晶格振动谱,给出了它们的综合结果。半导体中杂质诱发定域模已被人们广为研究,作者主要以自己的结果阐述了禁带模、共振模、准定域模和非晶态半导体振动谱研究在近年来取得的重要进展。除以较多篇幅研究各种定域化振动模的位置外,本文还从键—电荷模型出发讨论了杂质诱发振动吸收带的强度。