33 μm free standing thick film vertical structure LED made by laser lift‐off

Abstract

The 33 μm thick film vertical structure LEDs without any substrate were fabricated and their free standings were successfully realized by laser lift‐off and HVPE technology. Through the AFM analyses we know that the laser irradiation can causes big damage to the wafer. However, since the 33 μm thick film vertical structure LEDs without any substrate have longer distance between the laser irradiating plane and the quantum well than the the thin film (3‐4 μm) vertical structure LED on Cu or Si substrate, the 33 μm free standing thick film vertical structure LEDs exhibited good electrical and optical characteristics for the less damage on the quantum well caused by the laser lift off process. It has also been proved that the 33 μm thick film vertical structure LEDs without any substrate has lower thermal series resistance than the vertical structure LEDs on 300‐400 μm free standing GaN substrate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Quasi-homoepitaxial GaN-based blue light emitting diode on thick GaN template

“…Recently, some researchers have reported that InGaN/GaN MQW LED had grown on about 30-µm-thick HVPE GaN template. [15,16] Both of them observed the improvements of crystal quality and luminous efficiency of the LEDs on thick GaN template. Sun et al also showed that the LLO process had less degraded effect on the LED on thick template than that on a conventional buffer layer.…”

“…In spite of the above advantages of a thick GaN template, there are not many works reported on the GaN-based LED on thick GaN template. [11,[14][15][16] The GaN template is a virtual substrate since the real substrate underneath is sapphire. Hence, we call the regrowth on the GaN template "quasi homoepitaxy".…”

“…Sun et al also showed that the LLO process had less degraded effect on the LED on thick template than that on a conventional buffer layer. [15] Actually, the growth on the thick GaN template is reported much less than that on the GaN substrate. Besides, growth surface treatment to eliminate the interface between HVPE-GaN and MOCVD-GaN [17,18] and optimization of growth condition to inherit the low TDD and residual strain of HVPE-GaN [19,20] for GaN substrates are also essential to regrowth on the thick GaN template.…”

Auto-Split Laser Lift-Off Technique for Vertical-Injection GaN-Based Green Light-Emitting Diodes

“…However, the fabrication procedure of V-LEDs was proved complicated. Inductively coupled plasma (ICP) is usually used twice for etching away the u-GaN, for electric current isolation and for defining the chip size [27]- [29]. In our recent work, a new method called auto-split LLO technique is proposed in which ICP etching is used once and the definition of chip size is completed simultaneously during the removal of the sapphire substrate by LLO [30].…”

GaN-based LEDs with a high light extraction composite surface structure fabricated by a modified YAG laser lift-off technology and the patterned sapphire substrates

“…Nowadays, as GaN-based LEDs are widely used and the demand for high-brightness LEDs increases, improving LED efficiency is the most important task for the development of GaN-based LED technologies [1][2][3][4]. However, due to the small critical angle, such as absorption of light within the device, the light extraction efficiency (LEE) of LEDs is still very low [5,6].…”