蓝光-宽带隙激光器课件

1、Wide BandgapSemiconductor-Based Lasers,2014-1-9,1,学习交流PPT,Part 1：GaN blue laser diodes,2,学习交流PPT,彩色激光显示 打印和扫描：快速、高分辨率 存储：CD(780 nm)AlGaAs基激光器 VCD(635 nm或650 nm)AlGaInP激光器 DVD(410nm) InGaN 激光器,1-1 Application,3,学习交流PPT,提高物镜的数值孔径NA值 容量与光源波长的2次方成反比 光学元部件及光盘片材料的光学透过率等限制,1-2 Optical Storage,400-430 nm,19

2、82年 AlGaAs/GaAs(780nm)异质结 激光器作为光源的CD播放机,1985年，Kabayashi InGaAlP(670nm)红光 激光器的室温连续激射,1992年，Hiroyama InGaAlP(630nm)红光 半导体激光器,1996年，日亚和中村 GaN(400nm)蓝紫光 半导体激光器,1999年，日亚实现商品化 GaN(400nm)蓝光半导体激光器 寿命10000h,4,学习交流PPT,1-3 Difficulties and Breakthroughs,难点 缺乏晶格常数匹配、热胀系数接近的热稳定的衬底材料 p型GaN外延层难以获得 突破 高质量GaN外延层的生长

3、1986年Amano利用低温生长的AlN或GaN过渡层或成核层,得到表面平坦如镜低剩余载流子浓度、高电子迁移率和高荧光效率的高质量GaN外延层,1991 年首次获得GaN外延层室温光泵浦下的受激发射。 低阻p-GaN 的获得 1989年Amano等人利用低能电子辐照实现了Mg掺杂低阻p型GaN。1991年Nakamura等人在700以上无氢的氮气氛中退火 ,也获得了低阻p-GaN。 高质量InGaN外延层的生长 有源层内由 In 组分涨落引起的深局域化能态是发光二极管高效发光的关键 ,只有掺有In的GaN有源层才可能得到室温带间跃迁。,5,学习交流PPT,1-4 Growth,衬底的选择,生长

4、技术 双流生长技术 外延侧向过生长 悬挂式外延,6,学习交流PPT,F-P腔结构InGaN基激光器 电注入的三级Bragg光栅紫光DFB激光器,1-5 Cavity structure,垂直腔面发射激光器 极化声子激光器,7,学习交流PPT,Part 2：GaN-Based VCSEL and GaN-/ZnO-Based,8,学习交流PPT,2-1 Introduction,microcavity (MC)-based VCSEL polariton lasers,With edge-emitting GaN-based lasers in commercial systems, atten

5、tion is shifting to more demanding and rewarding emitters.,High-speed, high-resolution laser printing and scanning New types of coherent optical but nearly thresholdless sources,Observation of spontaneous em-ission buildup in polariton lasing emission is attributed to a Bose Einstein condensate of c

6、avity pol-aritons.,9,学习交流PPT,2-2 GaN-BASED VCSEL,The beam of a VCSEL is characterized by a lower divergence angle compared with that of the edge-emitting lasers, making them favored for use in fiber-optic communications. Gain region is very short in vertical cavity devices as compared the edge-emitt

7、er varieties, the required reflectivities of the top and bottom DBRs must be well above 90% in order to overcome optical losses for lasing.,VCSELs emit perpendicular to the active region surface, allowing their fabrication in a dense two-dimensional array.,10,学习交流PPT,2-2-1 Optically Pumped GaN-Based

8、 VCSEL(1),A significant narrowing of the emission spectra from 2.5 nm to 0.1 nm above the threshold was observed, which is direct evidence of lasing os-illation in the In0.1Ga0.9N VCSEL.,Science 17 September 1999: Vol. 285 no. 5435 pp. 1905-1906,Lasing action was observed at a wavelength of 399 nm u

9、nder optical excitation and confirmed by a narrowing of the linewidth in the emission spectra from 0.8 nm below threshold to less than 0.1 nm above threshold.,Bottom DBR: 43-pair GaN/Al0.34Ga0.66N Cavity: 26 sets of In0.01Ga0.99N/In0.1Ga0.9N MQWs Top DBR:15-pair ZrO2/SiO2,11,学习交流PPT,2-2-1 Optically

10、Pumped GaN-Based VCSEL(2),Top/Bottom DBR: SiO2/HfO2 Cavity: InGaN/GaN/AlGaN QW heterostructure,Demonstrated a cavity Q factor exceeding 600 in initial experiments, suggesting that the approach can be useful for blue and near ultraviolet RCLED and VCSEL.,Bottom DBR: 60-pair GaN/Al0.25Ga0.75N Cavity:

11、20 sets of In0.03Ga0.97N/InGaN MQWs Top DBR:15-pair SiO2/HfO2,Demonstrated quasi-continuous-wave (CW) lasing operation at room temperature using a hybrid cavity structure,12,学习交流PPT,2-2-1 Optically Pumped GaN-Based VCSEL(3),Exhibited a high Q factor of 460, a spontaneous emission factor of about 10-

12、2, and low threshold of 5.1mJ/cm-2.,Demonstrated the great potential offered by the lattice-matched AlInN/GaN material system to realise high quality MOVPE-grown advanced optoelectronic devices such as VCSELs on GaN quasi-substrates.,Top/Bottom DBR: SiO2/ZrO2 Cavity: three periods of In0.02Ga0.98N(5

13、nm)/In0.15Ga0.85N(2.5nm) QWs sandwiched between Al0.07Ga0.93N layers,Bottom DBR: 28-pair AlInN/GaN Cavity: 2 sets of In0.15Ga0.85N/GaN MQW Top DBR:23-pair AlInN/GaN DBR,Crack-free high reflectivity DBRs,13,学习交流PPT,2-2-1 Optically Pumped GaN-Based VCSEL(4),A low average threshold pump energy density

14、of 200 J/cm2 was achieved in a crack-free planar hybrid. This is also conducive for electrical injection.,Demonstrated an efficient current injection scheme in micron-scaled areas for high current density operation in vertical light emitting devices by using a LM AlInN oxidized layer. A current dens

15、ity of the order of 20 kA/cm2 has been achieved, a value which should fulfill the injection requirements for nitride-based VCSELs.,Bottom DBR: 39.5-pair Al0.82In0.18N/GaN Cavity: 3 sets of In0.14Ga0.86N/GaN QWs Top DBR:13-pair SiO2/Si3N4,14,学习交流PPT,2-2-2 Electrically Pumped GaN-Based VCSEL(1),电泵浦的Ga

16、N基VCSEL难点 (1)难以获得具有高质量和高反射率的DBR AlxGa1-xN和GaN之间折射率相差较大, 因此二者搭配而成的DBR为GaN基VCSEL所普遍采用。但AlxGa1-xN和GaN之间晶格失配严重, 它们的热膨胀系数也相差较大。 (2)缺少合适的p型接触电极材料 p型GaN的功函数很高, 很难找到理想的低阻欧姆接触电极材料。VCSEL的电流注入既要求低接触电阻又要求出光孔径具有非常低的光学损耗, 更增大了电极材料的难度。 解决方案：在AlN/GaN DBR的制造过程中引入了超晶格结构, 在出光孔径上以氧化铟锡(ITO)作为接触电极。,15,学习交流PPT,2-2-2 Elect

17、rically Pumped GaN-Based VCSEL(2),Bottom DBR: 29-pair AlN/GaN DBR three sets of a 5.5-pair of AlN/GaN superlattice was inserted every four pairs of AlN/GaN Cavity: n-GaN(790nm) ten periods of In0.2Ga0.8N(2.5nm)/GaN(7.5 nm) MQWs p-GaN(120nm) Top DBR:8-pair Ta2O5/SiO2 DBR,16,学习交流PPT,2-2-2 Electrically

18、 Pumped GaN-Based VCSEL(3),Bottom DBR: 7-pair SiO2/Nb2O5 Cavity: n-GaN(790nm) 2-pair of InGaN (9nm)/GaN (13nm) MQWs p-GaN(120nm) Top DBR:11.5-pair SiO2/Nb2O5,Fabricated a vertical-current-injection GaN-based VCSEL Lasing action at RT was realized under CW current operation.,17,学习交流PPT,2-3 Wide Bandg

19、ap Semiconductor Polariton Devices,在1996年Imamoglu及其合作者提出了极化声子激光器的概念,他们是基于一种叫激子极化声子的准粒子提出此概念，这种准粒子由光和物质组成，产生于适当设计的半导体晶体结构中。,Polariton,BoseEinstein condensation,Lasing Condition,Polariton Lasers,Extremely low threshold lasers,1998年，Le Si Dang与其合作者在液氦温度下观察到极化激光。 2007年，Southampton和Lausanne团队实现了具有光泵的第一个室

20、温极化声子激光器。 2012年，Iorsh基于氮化镓（GaN）微腔的电泵浦极化声子激光器优化方案。,18,学习交流PPT,2-3-1 GaN-Based Microcavities-Polariton Lasers,A realistic model for a room temperature polariton laser has been proposed for a GaN MC . It shows an extremely low threshold power at room temperature and a high quantum efficiency.,Bottom DB

21、R: 11-pair Al0.2Ga0.8N/Al0.9Ga0.1N Cavity: 9 GaN QWs four monolayers Top DBR:14-pair Al0.2Ga0.8N/Al0.9Ga0.1N,Bottom DBR: 34-pair Al0.85In0.15N/Al0.2Ga0:8N Cavity: bulk GaN Top DBR:10-pair SiO2/Si3N4,Observe a room-temperature low-threshold transition to a coherent polariton state in bulk GaN microca

22、vities in the strong-coupling regime. A clear emission threshold of 1 mW, 1 order of magnitude smaller than the best optically pumped (In,Ga)N quantum-well VCSELs,19,学习交流PPT,2-3-2 ZnO-Based Microcavities(1),Another wide-bandgap semiconductor, ZnO, is an attractive candidate for UV optoelectronics de

23、vices. ZnO has an exciton binding energy (60 meV) that is more than twice that of GaN (26 meV).,Bottom DBR: 29-pair Al0.5Ga0.5N/GaN Cavity: bulk ZnO Top DBR:8-pair SiO2/Si3N4,Rabi splitting,A large vacuum Rabi splitting of 50 meV at RT was obtained,which is larger than that observed in bulk GaN-base

24、d MCs. Results indicate that ZnO-based microcavities can be used to realize polariton lasers.,20,学习交流PPT,2-3-2 ZnO-Based Microcavities(2),Bottom DBR: a 30-pair AlN/Al0.23Ga0.77N Cavity: bulk ZnO Top DBR:9-pair SiO2/HfO2,The strong exciton-photon coupling at RT has been observed from the ZnO-based hy

25、brid microcavity structure. Large vacuum Rabi splitting value: about 58 meV,21,学习交流PPT,3. CONCLUSION,Introduce wide bandgap semiconductor laser, including applications, especially in Optical Storage, difficulties and breakthroughs, growth techniques and cavity structures.,Reviewed the recent progres

26、s in wide-bandgap semiconductor-based surface-emitting laser structures such as GaN-based VCSELs and GaN-/ZnO-based polariton lasers.,22,学习交流PPT,References,The blue laser diode 半导体蓝光激光器 Wide Bandgap Semiconductor-Based Surface-Emitting Lasers Lasing emission from an InGaN VCSEL 宽禁带 GaN 基半导体激光器进展 GaN

27、基蓝光半导体激光器的发展 蓝光激光器的应用与发展 A vertical cavity light emitting InGaN quantum well heterostructure Near ultraviolet optically pumped vertical cavity laser 低维半身傩结构材料及其器件应用研究迹展 为什么我们需要极化声子激光器? 电注入连续波蓝光GaN基 Cavity polaritons in ZnO-based hybrid microcavities Room-TemperaturePolariton Lasing in Semiconductor Microcavities 垂直腔面发射激光器 半导体泵浦全固体蓝光激光器的研究进展 Low-threshold lasing of InGa