自分裂GaN基垂直结构LED研究

Research on Auto-split GaN-based Vertical Structure LED

为了解决感应耦合等离子体刻蚀和衬底切割对发光二极管芯片造成损伤的问题,提高器件的成品率,提出了一种新的制备氮化镓基垂直结构发光二极管的工艺方法,成功制备出了无需衬底切割的自分裂垂直结构发光二极管.制备过程中使用化学机械抛光来代替感应耦合等离子体刻蚀对n型氮化镓进行减薄,避免了感应耦合等离子体刻蚀对器件侧壁和有源区造成的损伤;通过临时衬底转移技术解决了衬底切割的问题,无需衬底切割即可得到单个发光二极管芯片.与传统结构正装发光二极管相比,300μm×300μm的自分裂垂直结构发光二极管的电学特性得到大幅度改善,电流为20 mA下的正向电压从3.17 V降到2.88 V,降低了9%;饱和电流从240 mA提高到280 mA,提高了17%.研究了电极形状对器件性能的影响,将电极形状由圆盘形改为环形,500μm×500μm的自分裂垂直结构发光二极管的饱和电流从450 mA提高到490 mA,提高了9%,通过优化电极结构有望进一步改善芯片性能.

In order to solve the problem of damage to LED chip caused by inductively coupled plasma etching and substrate cutting,and improve the yield of devices,a new process for fabricating GaN-based vertical structure LED is proposed.The auto-split vertical structure LED without substrate cutting is successfully fabricated.In the process of device preparation,chemical mechanical polishing is used to reduce the thickness of n-GaN instead of inductively coupled plasma etching,which avoids the damage to the side wall and active region of the device caused by inductively coupled plasma etching.The problem of substrate cutting is solved by temporary substrate transfer technology,and a single LED chip can be obtained without substrate cutting.Compared with the regular LED,the electrical characteristics of 300μm×300μm auto-split vertical structure LED are greatly improved.The forward voltage at 20 mA decreases from 3.17 V to 2.88 V,which decreases by 9%;the saturation current increases from 240 mA to 280 mA,increasing by 17%.The influence of electrode shape on the device performance is studied.The electrode shape is changed from disk shape to ring shape,the saturation current of 500μm×500μm auto-split vertical structure led is increased from 450 mA to 490 mA,which is increased by 9%.The performance of auto-split vertical structure LED is expected to be improved by optimizing the electrode structure.