GaN基激光器多量子阱结构的性能表征与结构优化

研究了包括四元合金在内的三种多量子阱结构,对以此为有源层的激光器进行了性能表征和比较分析.通过对阈值电流和外微分量子效率的测量以及增益分布的模拟分析,证实了四元合金用于量子阱结构生长对提高激光器性能的作用.此外对优化的量子阱结构激光器的漏电流和增益饱和带来的影响进行了研究.     

GaN基激光器多量子阱结构的性能表征与结构优化

研究了包括四元合金在内的三种多量子阱结构,对以此为有源层的激光器进行了性能表征和比较分析.通过对阈值电流和外微分量子效率的测量以及增益分布的模拟分析,证实了四元合金用于量子阱结构生长对提高激光器性能的作用.此外对优化的量子阱结构激光器的漏电流和增益饱和带来的影响进行了研究.     

干法刻蚀对InAsP/InGaAsP应变多量子阱发光特性的影响

采用气态源分子束外延(GSMBE)生长了具有不同阱宽的InAsP/InGaAsP应变多量子阱,并对干法刻蚀前、干法刻蚀及湿法腐蚀不同厚度覆盖层后的多量子阱光致发光(PL)谱进行了表征.测量发现干法刻蚀量子阱覆盖层一定厚度后量子阱光致发光强度得到了明显的增强.这与干法刻蚀后量子阱覆盖层表面粗糙度变化及量子阱内部微结构变化有关.     

干法刻蚀对InAsP/InGaAsP应变多量子阱发光特性的影响

采用气态源分子束外延(GSMBE)生长了具有不同阱宽的InAsP/InGaAsP应变多量子阱,并对干法刻蚀前、干法刻蚀及湿法腐蚀不同厚度覆盖层后的多量子阱光致发光(PL)谱进行了表征.测量发现干法刻蚀量子阱覆盖层一定厚度后量子阱光致发光强度得到了明显的增强.这与干法刻蚀后量子阱覆盖层表面粗糙度变化及量子阱内部微结构变化有关.     

掺Si对AlGaInP/GaInP多量子阱发光性能的影响

研究了Si掺杂对MOCVD生长的(Al0.3Ga0.7)In0.5P/Ga0.5In0.5P多量子阱发光性能的影响.样品分为两类:一类只生长了(Al0.3Ga0.7)In0.5P/Ga0.5In0.5P多量子阱结构;另一类为完整的多量子阱LED结构.对于只生长了(Al0.3Ga0.7)In0.5P/Ga0.5In0.5P多量子阱结构的样品,掺Si没有改变量子阱发光波长,但使得量子阱发光强度略有下降,发光峰半高宽明显增大.这应是掺Si使量子阱界面质量变差导致的.而在完整LED结构的情况下,掺Si却大大提高了量子阱的发光强度.相对于未掺杂多量子阱LED结构,垒层掺Si使多量子阱的发光强度提高了13倍,阱层和垒层均掺Si使多量子阱的发光强度提高了28倍,并对这一现象进行了讨论.     

掺Si对AlGaInP/GaInP多量子阱发光性能的影响

研究了Si掺杂对MOCVD生长的（Al0.3Ga0.7）In0.5P/Ga0.5In0.5P多量子阱发光性能的影响．样品分为两类：一类只生长了（Al0.3Ga0.7）In0.5P/Ga0.5In0.5P多量子阱结构;另一类为完整的多量子阱LED结构．对于只生长了（Al0.3Ga0.7）In0.5P/Ga0.5In0.5P多量子阱结构的样品,掺Si没有改变量子阱发光波长,但使得量子阱发光强度略有下降,发光峰半高宽明显增大．这应是掺Si使量子阱界面质量变差导致的．而在完整LED结构的情况下,掺Si却大大提高了量子阱的发光强度．相对于未掺杂多量子阱LED结构,垒层掺Si使多量子阱的发光强度提高了13倍,阱层和垒层均掺Si使多量子阱的发光强度提高了28倍,并对这一现象进行了讨论．     

InGaAs／GaAs多量子阱SEED设计和特性研究

本文分析了计算了InGaAs/GaAs多量子阱（SEED）的激子吸收行为,对器件的多量子阱及谐振腔结构进行了设计和理论分析,用MOCVD系统生长了多量子阱外延材料,并且对器件的反射谱和光电流谱特性进行了测试。     

Design and Characteristics of InGaAs/GaAs MQW SEED Arrays Structure

讨论了谐振腔中的DBR对InGaAs／GaAs多量子阱SEED面阵光反射特性的影响．采用InGaAs／GaAs作为多量子阱SEED器件的有源区,从而获得了980nm工作波长．设计和分析了InGaAs／GaAs多量子阱SEED中的一种用于倒装焊的新型谐振腔结构．多量子阱材料是用MOCVD系统生长,利用微区光反射谱、PL谱以及X射线双晶衍射对多量子阱材料进行了测量和分析,测量结果表明多量子阱材料具有良好的质量,证明了器件结构的设计和分析是准确的．     

AlGaAs/GaAs-MQW激光器光增益谱理论和实验

本文简明地描述了由载流子带内弛豫加宽的半经典的密度矩阵理论.根据该理论计算了AlGaAs/GaAs多量子阱激光器的线性偏振光增益及量子阱宽L_x、Al_xGa_(1-x)As势垒层x值和带内弛豫时间τ_(in)对TE增益的影响.实验测量了多量子阱激光器的偏振光增益谱.理论与实验进行了比较.     

InGaAs/GaAs多量子阱SEED面阵结构特性与设计

讨论了谐振腔中的 DBR对 In Ga As/ Ga As多量子阱 SEED面阵光反射特性的影响 .采用 In Ga As/ Ga As作为多量子阱 SEED器件的有源区 ,从而获得了 980 nm工作波长 .设计和分析了 In Ga As/ Ga As多量子阱 SEED中的一种用于倒装焊的新型谐振腔结构 .多量子阱材料是用 MOCVD系统生长 ,利用微区光反射谱、PL 谱以及 X射线双晶衍射对多量子阱材料进行了测量和分析 ,测量结果表明多量子阱材料具有良好的质量 ,证明了器件结构的设计和分析是准确的     

光调制反射谱用于研究MBEGaAs1—xSbx／GaAs外延膜

本文讨论了量子阱的光调制反射谱(PR)线形,并采用光调制反射谱研究了MBE GaAs_(1-x)Sb_x/GaAs异质结、应变层量子阱。可见,用PR谱研究MBE外延膜具有一定的优越性。     

Optically pumped four-level infrared laser based on intersubbandtransitions in multiple quantum wells: feasibility study

The feasibility of optically pumped infrared laser based on the intersubband transitions in multiple quantum wells is studied theoretically. The criteria for population inversion and efficient lasing operations are established. A system consisting of a superlattice with four quantum wells per period is proposed and shown to satisfy the criteria. The relaxation processes are investigated, giving the electron-phonon interaction a rigorous theoretical treatment. It is shown that in the proposed structure, optical gain in excess of 300 cm ^-1 can be realized under practical pumping conditions. Modification and optimization of the proposed laser are discussed     

In_（0．2）Ga_（0．8）As／GaAs应变多量子阱结构的光调制反射和热调制反射谱的研究

对Ｉｎ（０．２）Ｇａ（０．８）Ａｓ／ＧａＡｓ应变多量子阱在７７Ｋ下的光调制反射谱（ＰＲ）和热调制反射谱（ＴＲ）进行了实验研究．对ＰＲ结果的线形拟合指认了应变多量子阱中子能级的跃迁，并与理论计算结果作了比较．实验对比确认ＰＲ中１１Ｈ、１３Ｈ等跃迁结构为非耦合态、具有电场调制机构的一阶微商性质．而１１Ｌ、３１Ｈ、２２Ｈ等跃迁结构为阶间耦合态，对这些隧穿耦合的低场调制产生三阶微商特性．     

Growth and optical characterization of strained CdZnTe/ CdTe quantum wells

We have grown strained Cd_1-xZn_xTe(x ≈ 0.2)/CdTe single and multiple quantum wells by molecular beam epitaxy. GaAs was used as a substrate. The well widths were systematically increased until the critical thickness was exceeded. Low-temperature (liquid helium) photoluminescence (PL) spectroscopy was used to characterize the films. Two prominent PL peaks were observed: one arising from the quantum well and the other from the barrier material. The energy of the quantum well luminescence is consistent with theory when strain is included. The critical layer thickness for the CdTe quantum wells was found to be between 150 and 175 å, in agreement with the model of Matthews and Blakeslee.     

Resonant cavity enhanced photoluminescence of tensile strained Ge/SiGe quantum wells on silicon-on-insulator substrate

The tensile strained Ge/SiGe multiple quantum wells （MQWs） grown on a silicon-on-insulator （SOI） substrate were fabricated successfully by ultra-high chemical vapor deposition. Room temperature direct band photoluminescence from Ge quantum wells on SOI substrate is strongly modulated by Fabry-Perot cavity formed between the surface of Ge and the interface of buried SiO2. The photoluminescence peak intensity at 1.58 μm is enhanced by about 21 times compared with that from the Ge/SiGe quantum wells on Si substrate, and the full width at half maximum （FWHM） is significantly reduced. It is suggested that tensile strained Ge/SiGe multiple quantum wells are one of the promising materials for Si-based microcavity lijzht emitting devices.     

Si基Ge/SiGeⅠ型量子阱结构的理论设计和实验研究

基于能带工程理论,设计了Si基Ge/SiGeⅠ型量子阱结构。采用超高真空化学气相淀积系统,制备出高质量的Si基Ge/SiGe多量子阱系列材料。当样品中Ge量子阱宽从15nm减少到12nm和11nm时,室温下荧光(PL)光谱观测到量子限制效应引起的直接带跃迁发光峰位的蓝移,峰位的实验值与理论值符合得很好;当Ge量子阱宽逐渐减小到9nm和7nm时,测试得到样品的PL谱峰位却与理论预期出现了较大的差值。进一步的实验表明,这主要是由于量子阱厚度小到一定程度时,量子阱的直接带发光受到抑制,其发光主要源于Ge虚拟衬底。     

GaAs／AlGaAs多量子阱红外探测器的光电流谱

测量了ＧａＡｓ／ＡｌＧａＡｓ多量子阱红外探测器在零偏压、小偏流和大偏压等条件下的光电流谱，并结合理论计算的光跃迁能量讨论了光电流谱的多峰结构和异常增强特性。     

Optimization of electrode shape for high power GaN-based light-emitting diodes

Because the polarization effect influences the distribution of the carriers in the multiple quantum wells of the light-emitting diodes （LEDs）, the light-emitting efficiency is also affected. The influence of the polarization effect on GaN-based LEDs＇ performance is simulated. By simulating four different types of electrode shapes, it＇s found that the electrode shape influences not only the photoelectric characteristics but also the optical absorption by the semiconductor. Through the optimization of the electrode shape, the I-V characteristic is improved, and the series resistance is lowered. The optical absorption by the semiconductor is decreased and then the heat generated in the LEDs is lowered. As a result, both the photoelectric conversion efficiency and the stability are improved.     

Low-Temperature photoluminescence of SiGe/Si disordered multiple quantum wells and quantum well wires

Low-temperature photoluminescence from disordered SiGe/Si quantum wells and quantum wires made from periodic quantum wells by electron beam lithography and reactive ion etching has been measured. No enhancement in luminescence is seen, compared to that in periodic quantum wells, in the disordered wells or quantum wires. New transitions are observed in the wire luminescence, including a possible no-phonon transition exhibiting a 32 meV blue shift compared to the same transition in the wells.     

多量子阱有效折射率偏振相关性研究

分析了多量子阱材料各参数对其TE模和TM模有效折射率的影响。结果表明:阱数增多,多量子阱有效折射率降低,当量子阱数目大于3时,其有效折射率的变化不明显。垒厚增加,有效折射率略有降低。存在合适的张应变量使TE模和TM模有效折射率峰值波长接近的同时,折射率差值整体最小,偏振相关性最小。据此提出多量子阱材料有效折射率低偏振相关设计方法,并设计出C波段内(1530~1565 nm)折射率低偏振相关的InGaAs/InGaAsP多量子阱材料。研究结果有助于设计实用化的有效折射率低偏振相关量子阱材料。