GaN-on-Si blue/white LEDs: epitaxy, chip, and package
GaN-on-Si blue/white LEDs: epitaxy, chip, and package
复制标题
硅基氮化镓蓝/白光 LED：外延、芯片和封装
DOI：
10.1088/1674-4926/37/4/044006
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发表时间：
2016-04-01
影响因子：
5.1
通讯作者：
Yang Hui
中科院分区：
文献类型：
--
作者：
Sun Qian;Yan Wei;Yang Hui
通过学术界和工业界的共同研发努力，在大直径硅上外延集成III-氮化物半导体的梦想正在实现，这是由于硅基GaN技术在提高效率方面的巨大潜力，同时大大降低了固态照明和电力电子的制造成本。由于GaN的热膨胀系数(CTE)和晶格常数的大失配，在Si衬底上生长高质量的GaN是非常具有挑战性的，通常会导致GaN薄膜中出现微裂纹网络和高密度的线位错(TDS)。Al组分梯度的AlGaN/AlN缓冲层不仅在高温生长过程中建立了压缩应变以补偿冷却过程中产生的拉应力，而且还过滤掉了TDS以在Si衬底上获得无裂纹的高质量n-GaN薄膜，在Bar2上的(0002)和(10(1))衍射面的X射线摇摆曲线宽度均小于300弧秒。在GaN-on-Si模板上，在p-AlGaN和p-GaN层沉积之前，在高质量的InGaN/GaN多量子阱(MQW)上生长了精心设计的V-缺陷，以屏蔽TDS作为非辐射复合中心，并通过类过孔结构增强对MQW的空穴注入。将生长的GaN-on-Si LED晶片加工成具有反射p电极的垂直结构薄膜LED芯片，并在去除外延Si(111)衬底后对N面表面进行粗化，以提高光提取效率。在350mA的注入电流下，1 mm(2)GaN-on-SiLED芯片的平均效率为150-160lm/W，并通过了10000-hLM80可靠性测试。所生产的GaN-on-Si LED具有单面均匀发射和接近朗伯分布的特点，可以采用晶圆级荧光粉涂层工艺，适用于定向照明、相机闪光灯、路灯、汽车前大灯和其他照明应用。
The dream of epitaxially integrating III-nitride semiconductors on large diameter silicon is being fulfilled through the joint R&D efforts of academia and industry, which is driven by the great potential of GaN-on-silicon technology in improving the efficiency yet at a much reduced manufacturing cost for solid state lighting and power electronics. It is very challenging to grow high quality GaN on Si substrates because of the huge mismatch in the coefficient of thermal expansion (CTE) and the large mismatch in lattice constant between GaN and silicon, often causing a micro-crack network and a high density of threading dislocations (TDs) in the GaN film. Al-composition graded AlGaN/AlN buffer layers have been utilized to not only build up a compressive strain during the high temperature growth for compensating the tensile stress generated during the cool down, but also filter out the TDs to achieve crack-free high-quality n-GaN film on Si substrates, with an X-ray rocking curve linewidth below 300 arcsec for both (0002) and (10 (1) over bar2) diffractions. Upon the GaN-on-Si templates, prior to the deposition of p-AlGaN and p-GaN layers, high quality InGaN/GaN multiple quantum wells (MQWs) are overgrown with well-engineered V-defects intentionally incorporated to shield the TDs as non-radiative recombination centers and to enhance the hole injection into the MQWs through the via-like structures. The as-grown GaN-on-Si LED wafers are processed into vertical structure thin film LED chips with a reflective p-electrode and the N-face surface roughened after the removal of the epitaxial Si(111) substrates, to enhance the light extraction efficiency. We have commercialized GaN-on-Si LEDs with an average efficacy of 150-160 lm/W for 1mm(2) LED chips at an injection current of 350 mA, which have passed the 10000-h LM80 reliability test. The as-produced GaN-on-Si LEDs featured with a single-side uniform emission and a nearly Lambertian distribution can adopt the wafer-level phosphor coating procedure, and are suitable for directional lighting, camera flash, streetlighting, automotive headlamps, and otherlighting applications.