Abstract:在高强度光激发的Ge、GaAs和ZnSe中观察到电子-空穴等离子体.采用远红外磁光吸收和光致发光两种手段研究了等离子体的空间膨胀.将Ge的远红外磁光吸收谱中的一个低磁场峰指认为快速扩展的电子-空穴-等离子体中的空穴在价带间的跃迁,用磁场限制扩散模式解释了时间和空间分辨测量结果.半绝缘GaAs中电子-空穴-等离子体的膨胀与扩散常数有关,而扩散常数取决于激发强度,这就提示了膨胀是由于“声子风”(phonon wind)而引起的.在用MOVPE方法生长的ZnSe外延层中也观察到均匀的等离子体.用非-k选择定则能很好地拟合光致发光谱线型,多体效应引起的带隙收缩与在其它Ⅱ-Ⅵ族化合物中观察到的类似,并首次观察到ZnSe外延层中的电子回旋共振.

Abstract:根据一维分子链中的电荷密度波(CDW)和价键序量波(BOW)统一地研究了MX络合物和高分子中的三阶光学非线性.揭示了Pt-Cl络合物和聚乙炔的三次谐波产生频谱共振峰结构的物理来源:Pt-Cl络合物的1.8eV峰和聚乙炔的0.9eV峰都是由能带间的双光子共振产生的.本理论能定量地阐明这两种材料的已观察到的三阶光学非线性的实验数据,还能预测Pt-Cl络合物的三次谐波在0.9eV处存在另一个由三光子共振引起的峰.

Abstract:通过分子束外延生长不同组分的Ge_xSi_(1-x)标样,测量其俄歇谱(dN/dE～E),得到了在指定的实验条件下Ge(LMM)和Si(KLL)幅度之比与Ge组分x的关系,与只用纯Ge和纯Si原子灵敏度因子之比计算结果差别很小.证明俄歇电子谱是组分x原位测量的有效手段,相对误差在10%以内.讨论了Ge的偏析现象,在x>0的情况下Ge偏析不致于影响上述测量方法的准确性.

Abstract:在温度为0.3～4.2K,磁场强度为0～7T的范围内对两个不同组份的Hg_(1-x)Mn_xTe(N_A>N_D)样品进行了输运特性的研究.组份x=0.03的样品在弱磁场(B<0.6T)下出现磁阻振荡,用修正的Pidgeon-Brown模型拟合各振荡峰值位置,得到共振受主能级随温度降低而升高,表明受主共振态已形成束缚磁极化子(RABMP).组份x=0.065的样品出现阶段性下降负磁阻行为,理论分析表明这是受主能级钉扎费密能级并在强场(B～1.5T)通过a_v(-1)价带顶引起价带空穴散射增强.两个样品都呈现负磁阻行为,但从磁阻的各向异性及能带分析表明其机理有所不同.

Abstract:提出了一个理论模型并用它圆满地解释了具有准二维层状结构高T_c氧化物超导体的表面阻抗Z_s(T,ω)对频率和温度的依赖性.运用Allender模型考虑了Cu-O链的作用,得到了YBa_2Cu_3O_(7-δ)(YBCO)的电导率的修正公式为(?)=In(Δ/hω)[C_1exp(-Δ/K_BT)+(1-C_1)K_BT/Δ],根据该模型和YBCO不同频率下表面电阻R_s(T)的实验数据计算了材料的磁穿透深度λ(T),理论计算结果和普通超导体的结果符合很好.

Abstract:采用电容耦合法测量了Ge_xSi_(1-x)/Si应变层超晶格在不同温度下的光伏特性.在Ⅱ型能带排列的样品中观测到价带-导带子带和价带子带-导带光跃迁的4个峰.对所有样品测得的光伏截止波长都比理论预期值小.还对光电压随温度的变化作了初步解释.

Abstract:MOVPE growth of GaAs/Al_xGa_(1-x)As superlattices and their applications inrelative photoelectric devices are reported. Epilayer quantum heterostructures are charac-terized by using cross-sectional transmission electron microscopy (XTEM). In SelfElectrooptic Effect Devices (SEED), the superlaltice interfaces are abrupt and the barrierand well layers keep good uniformity. In some High Electron Mobility Transistors(HEMT), superlattices used as buffer layers smooth out the growing surface roughness.

Abstract:The transport properties of a kind of quasi-periodical one-dimensional systemhave been studied. This system consists of a series of Fibonacci coupled quantum dots. Byusing the transfer matrix method, and taking account of the experiment techniques, theformalism of the electron transmission rate for the chain of quantum dots is proposed, andthe relationship between the conductance, magnetic field and voltage is discussed. From thenumerical results, it has been found that the transmission spectra of the system have richstructures, depending on the coupling among quantum dots.

Abstract:Diffusion of Zn into InP, InGaAsP and InGaAsP/InP single heterostructureshas been studied. The depth of the diffusion front is found to be proportional to the squareroot of the diffusion time. For single heterostructures the junction depth is dependent onthe InGaAsP epilayer thickness x_0, i.e. x_j/t~(1/2)=-x_0/(rt~(1/2))+I, which is very useful inthe fabrication of many electronic and optoelectronic devices where heterostructures areused and Zn diffusion is necessary.

Abstract:The pump-probe method is employed to measure the temporal process of theoptical nonlinear absorption of CdS crystals and the effect of external electric field on theelectron-exciton interaction in CdS crystal, to reveal the origin and characteristic of thatoptical nonlinearity. By simulation numerically, the decay time of electron-exciton interac-tion is about 60ps while the external electric field is not applied to CdS crystal. And the ex-perimental result shows that the decay time can be extended by external electric field.

Abstract:Porous silicon material has been made out and its photoluminescence of wave-lengths down to green and blue ranges observed. On these bases electroluminescence with ayellow color by means of current injection has been primarily obtained.