Substrate Lifted-off AlGaN/AlGaN Lateral Conduction Thin-Film Light-Emitting Diodes Operating at 285 nm

We report on the substrate laser lift-off (LLO) in lateral conduction flip-chip (FC) deep-UV light-emitting diodes (LEDs) with peak emission wavelength at 285 nm. The AlGaN-based LED epilayer structure was grown on a low-defect 2 µm-thick AlN/sapphire template and processed into 3×3 small periphery pixel-LED arrays. The total p-contact area of the 9 pixel, single chip devices was 180 ×180 µm2. Our results show that the use of FC die assembly with epoxy underfilling the gap between the chip and the submount dramatically increase the yield of damage-free debonding of sapphire and the overlying AlN layer. Equally important, no noticeable degradation of the electrical and optical characteristics of the thin-film light emitters was observed following the LLO process.

[1]  Motoaki Iwaya,et al.  Laser lift-off of AlN/sapphire for UV light-emitting diodes , 2012 .

[2]  Paul S. Martin,et al.  High performance thin-film flip-chip InGaN–GaN light-emitting diodes , 2006 .

[3]  Monirul Islam,et al.  276 nm Substrate-Free Flip-Chip AlGaN Light-Emitting Diodes , 2011 .

[4]  S. Denbaars,et al.  Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening , 2004 .

[5]  Asif Khan,et al.  Dislocation reduction in high Al‐content AlGaN films for deep ultraviolet light emitting diodes , 2011 .

[6]  M. Asif Khan,et al.  III–Nitride UV Devices , 2005 .

[7]  Toru Nagashima,et al.  Deep-Ultraviolet Light-Emitting Diodes Fabricated on AlN Substrates Prepared by Hydride Vapor Phase Epitaxy , 2012 .

[8]  Dong-Sing Wuu,et al.  Performance of Flip-Chip Thin-Film GaN Light-Emitting Diodes With and Without Patterned Sapphires , 2010, IEEE Photonics Technology Letters.

[9]  Motoaki Iwaya,et al.  Development of high efficiency 255–355 nm AlGaN‐based light‐emitting diodes , 2011 .

[10]  Motoaki Iwaya,et al.  Improved Efficiency of 255–280 nm AlGaN-Based Light-Emitting Diodes , 2010 .

[11]  Grigory Simin,et al.  High-power deep ultraviolet light-emitting diodes basedon a micro-pixel design , 2004 .

[12]  V. Adivarahan,et al.  Sub-Milliwatt Power III-N Light Emitting Diodes at 285 nm , 2002 .

[13]  Grigory Simin,et al.  Lateral Current Crowding in Deep UV Light Emitting Diodes over Sapphire Substrates , 2002 .

[14]  Monirul Islam,et al.  A Hybrid Micro-Pixel Based Deep Ultraviolet Light-Emitting Diode Lamp , 2011 .