Especially , mesfet devices fabricated on lec si - gaas substrate have been adopted into very large - scale integration ( vlsi ) and monolithic microwave integrated circuit ( mmic ) extensively . therefore , it is necessary to study the influence of defects in substrate material of lec si - gaas on performance of mesfet to meet the need of design and fabrication of gaas ic 以液封直拉半绝缘gaas为衬底的金属半导体场效应晶体管( mesfet )器件是超大规模集成电路和单片微波集成电路广泛采用的器件结构，因此研究lec法生长si - gaas ( lecsi - gaas )衬底材料特性对mesfet器件性能的影响，对gaas集成电路和相关器件的设计及制造是非常必要的。
Based on the transferred - electron theory of the iii - v compound semiconductor and the research on the lock - on effect of the si - gaas pcss ' s , this paper proposes the monopole charge domain model similar to the guun or high - field domain to explain the peculiar switching phenomena occurring in the lock - on mode theoretically 本文基于gaas等?族化合物半导体的转移电子理论，结合半绝缘gaas光电导开关中特有的lock - on效应的研究，提出了类似于耿畴(高场畴或偶极畴)的单极电荷畴理论模型，对光电导开关lock - on效应的各种现象给出了理论解释。
The electronic pulse waveform of linear , non - linear and the critically transiting switching modes outputted from the si - gaas pcss ' s was observed and measured . especially , we repeatedly measured the bias field thresholds and lock - on field of the critical transiting mode from the linear to non - linear state 作者测试了半绝缘gaas光电导开关在线性、非线性以及从线性到非线性过渡的临界状态模式下输出的电脉冲波形，特别是反复测量了开关在临界状态下的偏置电场阈值和lock - on电场强度。
As recent research and productive practice showed , such conventional parameters as dislocation densiry ( epd ) , charge carrier concentration , mobility were not enough to evaluate the si - gaas material ' s quality , let alone revealing the relationship between the quality of material and the performance of devices . on the other hand , recent research showed that ab microdefects had direct relationship with device performance , whose density ( ab - epd ) was more important than epd for revealing the relationship between the quality of material and the performance of devices 近些年来的科研和生产实践均表明，现行的常规参数，如位错密度、载流子浓度、迁移率等对表征半绝缘砷化镓材料的质量是不充分的，特别是不能反映材料质量与器件性能之间的关系。近期的科研成果证明， ab微缺陷与器件性能有直接的关系，而且ab微缺陷密度( ab - epd )是比位错密度更加敏感、更加重要的参数。
Based on the theory mode , the delay time between the beginning of optical illumination and the onset of lock - on switching was calculated , and the transiting speed of electrons , the traversing velocity of the current filament , was obtained as well . the calculated results matched well the experimental results . taking advantage of the ultra - fast response characteristics of the devices , si - gaas pcss ' s are successfully applied to the broadening test of nanosecond laser pulses 应用单极电荷畴模型数值计算了lock - on效应的光、电时间延迟和载流子的渡西安理工大学硕士学位论文越速度（丝状电流穿越开关间隙的速度） ，所得计算结果与实验测试结果基本吻a利川半绝缘gaas光屯导开关的超快光l匕11向应灯性，成功地应川下纳秒激光脉冲展宽试验中，证明了开关可厂泛应川在超快光电响应和光电反馈网络中。
By means of chemical etching , microscope observation , eelectron probe x - ray micro - analyzer ( epma ) , the micro - distribution of c acceptor defect in lec si - gaas wafer is investigated , the results show that there is serious influence of the density and distribution of dislocations on the distribution of c impurity in wafer 本文通过ab腐蚀、 koh腐蚀，金相显微镜观察，透射电镜能谱分析，电子探针x射线微区分析，研究了液封直拉法生长的非掺半绝缘砷化镓( lec ， si - gaas )单晶中碳的微区分布。
Duo to the intrinsic characteristics of the gaas material , serai - insulating ( si ) gaas photoconductive semiconductor switches ( pcss " s ) have more obvious advantages in the performance of both high power and ultra - fast switching than those pcss " s made of other materials and then can be widely used in ultrahigh speed electronics , field of high power microwave generation and pulse forming ( pulse sources of high power ultra - fast electromagnetism , ultra - wide - band microwave generator ) 半绝缘gaas光电导开关( photoconductivesemiconductorswitches简称pcss ' s )具有兼备宽频带和高功率容量特性，使其在超高速电子学和大功率脉冲产生与整形技术领域(大功率亚纳秒脉冲源、超宽带射频发生器等)具有广泛应用前景。
They can dynamically change the distribution of electric field , carriers and current densities in pcss , caused output current to delay and also strengthen the local electric field enough to satisfy qualification of domain , and then cause avalanche . the time of delay is determined by the time of attaining the qualification of domain 非线性光电导开关的时间延迟效应则是由于半绝缘gaas材料中的el2深能级中心动态地改变开关中的电场、载流子浓度引起的；延迟时间的长短主要由满足成畴所需条件的时间决定。
Due to the intrinsic characteristics of the gaas material , semi - insulating ( si ) gaas pcss ' s have more obvious advantages in the performance of both high power and ultra - fast switching than those pcss ' s made of other materials . the gaas pcss ' s can take on the particular phenomenon of lock - on effect when the thresholds of activating optical energy and bias field , which the devices demand , are meted simultaneously 然而，由于gaas材料的固有特性，半绝缘gaas光电导开关在其工作性能上有明显的优点，特别是在一定的光能和电场阈值条件下， gaas光电导开关能产生lock - on效应现象，所以gaas光电导开关的器件研究和实际应用开发成为光电导开关研究者所关注的焦点。
