Interface states in Al_2O_3/AlGaN/GaN metal-oxide-semiconductor structure by frequency dependent conductance technique

Frequency dependent conductance measurements are implemented to investigate the interface states in Al2O3/AlGaN/GaN metal-oxide-semiconductor(MOS) structures. Two types of device structures, namely, the recessed gate structure(RGS) and the normal gate structure(NGS), are studied in the experiment. Interface trap parameters including trap density Dit, trap time constant τit, and trap state energy ETin both devices have been determined. Furthermore,the obtained results demonstrate that the gate recess process can induce extra traps with shallower energy levels at the Al2O3/AlGaN interface due to the damage on the surface of the AlGaN barrier layer resulting from reactive ion etching(RIE).     

读万卷书,行万里路

正灿烂的阳光照大地,也照亮了同学们的笑脸。为了给毕业班的同学们留下一段难忘的美好记忆,让同学们自由地放飞理想,安徽黄山市祁门县祁山小学组织六年级全体学生在市内进行实地研学活动。现在,大家随小记者一起去看看吧!播种希望——植树行动早晨,同学们到达黄山润一生态园。老师安排6名同学为一组,让大家齐心协力种植树苗。化身"园丁"的同学们开始植树,第一步是挖坑,要挖出深约30厘米、直径约40厘米的坑。瞧!拿起锄头的女生们丢下"女神包袱",     

我是快乐的“小不点”

正我是一个"小不点",身高只有148厘米,体重70斤。为此,我曾经非常烦恼。其实,我在班里不算特别矮。可是,一到球馆,我就"鸡立鹤群"了。球馆里,比我年龄大的球友比我高,比我年龄小的竟然也比我高!唉,我真想快快长高!为了让我长高,妈妈快要"疯"啦!她每天准备很多荤菜、素菜、乳制品,还要求我每天必须吃至少两种水果。更可怕的是,妈妈严格限制我吃零食,从原来的一周让我吃一次改成一月让我吃一次。     

Room-Temperature Continuous-Wave Operation of InGaN-Based Blue-Violet Laser Diodes with a Lifetime of 15.6 Hours

We report our recent progress of investigations on InGaN-based blue-violet laser diodes （LDs）. The roomtemperature （RT） cw operation lifetime of LDs has extended to longer than 15.6 h. The LD structure was grown on a c-plane free-standing （FS） GaN substrate by metal organic chemical vapor deposition （MOCVD）. The typical threshold current and voltage of LD under RT cw operation are 78 mA and 6.8 V, respectively. The experimental analysis of degradation of LD performances suggests that after aging treatment, the increase of series resistance and threshold current can be mainly attributed to the deterioration of p-type ohmic contact and the decrease of internal quantum efticiency of multiple quantum well （MQW）, respectively.     

Time delay in InGaN multiple quantum well laser diodes at room temperature

This paper reports that a long delay between the beginning of pumping current pulse and the onset of optical pulse is observed in InGaN laser diodes.The delay time decreases as the pumping current increases,and the speed of the delay time reduction becomes slower as the current amplitude increases further.Such delay phenomena are remarkably less serious in laser diodes grown on GaN substrate than those on sapphire.It attributes the delay to the traps which cause a large optical loss by saturable absorption and retard the laser action.The traps can be bleached by capturing injected carriers.The effect of GaAs laser irradiation on InGaN laser action demonstrates that the traps responsible for the delay are deep centres which can be filled by the photo-assisted processes.     

两环路核电厂试验支管振动疲劳研究

针对国内二代加的两环路核电厂试验用支管中存在的振动疲劳问题,提出了一种确定疲劳振动的测量和计算分析方法,并运用该方法对国内某两环路核电厂小支管进行了工况分析、振动测量和最大有效振动速度计算,同时采用结构力学有限元程序ANSYS软件对小支管的振动疲劳应力进行了分析.结果表明,该方法能够很好的诊断出小支管中存在的第一类敏感管和第二类敏感管,从而为判断在两环路核电厂中试验中支管是否是敏感管提供了理论依据.     

Thermal analysis of GaN laser diodes in a package structure

Using the finite-element method,the thermal resistances of GaN laser diode devices in a TO 56 package for both epi-up configuration and epi-down configuration are calculated.The effects of various parameters on the thermal characteristics are analysed,and the thicknesses of the AlN submount for both epi-up configuration and epi-down configuration are optimized.The obtained result provides a reference for the parameter selection of the package materials.