Photonic quantum ring laser and fabrication method thereof

Abstract

A photonic quantum ring (PQR) laser includes an active layer having a multi-quantum-well (MQW) structure and etched lateral face. The active layer is formed to be sandwitched between p-GaN and n-GaN layers epitaxially grown on a reflector disposed over a support substrate. A coating layer is formed over an outside of the lateral faces of the active layer, an upper electrode is electrically connected to an upper portion of the n-GaN layer, and a distributed Bragg reflector (DBR) is formed over the n-GaN layer and the upper electrode. Accordingly, the PQR laser is capable of oscillating a power-saving vertically dominant 3D multi-mode laser suitable for a low power display device, prevent the light speckle phenomenon, and generate focus-adjusted 3D soft light.

1 . A photonic quantum ring (PQR) laser, comprising:
 an active layer having a multi-quantum-well (MQW) structure and etched lateral face;   p-GaN and n-GaN layers, which are epitaxially grown, with the active layer sandwiched therebetween;   a reflector disposed over a support substrate and having the p-GaN layer thereon;   a coating layer formed over an outside of lateral faces of the active layer;   an upper electrode electrically connected to an upper portion of the n-GaN layer; and   a distributed Bragg reflector (DBR) formed over the n-GaN layer and the upper electrode.   
     
     
         2 . The PQR laser of  claim 1 , wherein the reflector is formed by using silver (Ag). 
     
     
         3 . The PQR laser of  claim 1 , wherein the DBR is formed by using a dielectric material in a TiO 2 /SiO 2  or SiN x /SiO 2  structure. 
     
     
         4 . The PQR laser of  claim 1 , wherein the DBR is formed in a GaN/Al x Ga 1−x N structure. 
     
     
         5 . The PQR laser of  claim 1 , wherein the active layer is formed by using InGaN or InAlGaN. 
     
     
         6 . The PQR laser of  claim 5 , wherein the PQR laser selects a light-emitting wavelength range by adjusting a composition ratio of indium (In) component and aluminum (Al) component contained in the active layer. 
     
     
         7 . The PQR laser of  claim 1 , wherein the PQR laser determines an inter-mode spacing (IMS) by adjusting the radius thereof. 
     
     
         8 . The PQR laser of  claim 1 , further comprising:
 a passivation layer formed between the active layer and the coating layer.   
     
     
         9 . The PQR laser of  claim 8 , wherein the passivation layer is formed by using SiN x  or SiO 2 . 
     
     
         10 . A fabrication method of a photonic quantum ring laser, comprising the steps of:
 forming, over a sapphire substrate, an n-GaN layer, an active layer, a p-GaN layer, and a reflector in order;   adhering a support substrate over the reflector and removing the sapphire substrate;   performing a selective etching to expose a lateral face of the active layer and forming a coating layer over an outside of the lateral faces of the active layer;   forming, over the coating layer, an upper electrode electrically connected to the n-GaN layer; and   forming a distributed Bragg reflector (DBR) in a region having the same width as the active layer and the n-GaN layer over the upper electrode and the n-GaN layer.   
     
     
         11 . The method of  claim 10 , further comprising the step of:
 before forming the coating layer, forming a passivation layer on the lateral face of the active layer exposed by the selective etching.   
     
     
         12 . The method of  claim 10 , wherein the passivation layer is formed by using SiN X  or SiO 2 . 
     
     
         13 . The method of  claim 10 , wherein the reflector is formed by using silver (Ag). 
     
     
         14 . The method of  claim 10 , wherein the DBR is formed by using a dielectric material in a TiO 2 /SiO 2  or SiN x /SiO 2  structure. 
     
     
         15 . The method of  claim 13 , wherein the DBR is formed in a GaN/Al x Ga 1−x N structure. 
     
     
         16 . The method of  claim 10 , wherein the active layer is formed by using InGaN or InAlGaN. 
     
     
         17 . The method of  claim 10 , wherein the sapphire substrate is removed by a laser lift-off (LLO). 
     
     
         18 . The method of  claim 10 , wherein the coating layer is formed by performing polyimide coating and polyimide planarization.