A Screen-Printed Sn-Based Substrate Technology for the Fabrication of Vertical-Structured GaN-Based Light-Emitting Diodes
A dicing-free substrate technology was proposed and demonstrated to simplify the fabrication of vertical-structured metal substrate GaN-based light-emitting diodes (VM-LEDs) using a Sn-based solder screen printing technique with patterned laser lift-off technology. As compared with conventional sapp...
Saved in:
| Published in | Japanese Journal of Applied Physics Vol. 49; no. 4; pp. 04DG10 - 04DG10-3 |
|---|---|
| Main Authors | , , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.04.2010
|
| Online Access | Get full text |
Cover
Loading…
| Summary: | A dicing-free substrate technology was proposed and demonstrated to simplify the fabrication of vertical-structured metal substrate GaN-based light-emitting diodes (VM-LEDs) using a Sn-based solder screen printing technique with patterned laser lift-off technology. As compared with conventional sapphire substrate GaN-based LEDs, VM-LEDs with an effective emission area of $1000\times 1000$ \mbox{$\mu$m} 2 were found to have a 0.38 (0.87) V reduction in forward voltage at 350 (700) mA. In addition, their enhancement in light output power in the current range of 350--700 mA was found to successively increase from 55 to 76%. By considering these results, the power conversion efficiency of VM-LEDs was found to be 2.14 times that of regular LEDs at 700 mA. |
|---|---|
| Bibliography: | (Color online) Schematic diagram of the fabrication processes of VM-LEDs with screen-printed Sn-based substrate. (a) Screen printing of Sn-based paste, (b) mounting a temporal substrate and patterned LLO process, and (c) surface roughening up to n-GaN and metal pad formation. (d) Schematic cross section of a regular GaN-based LED. Note that the device structures shown in the present figure were not drawn to scale. (Color online) SEM/OM images of samples in key processing states. (a) Top-view image of the sample after screening printing of Sn-based paste. (b) Top-view image of the patterned Sn-based substrates after reflow process. (c) 3D profile of the sample on the Sn-based metal substrate side. (d) Top-view image of the exposed n-GaN. (Color online) Comparison of typical forward $I$--$V$ characteristics of VM-LEDs and regular LEDs. (Color online) Comparison of typical $L_{\text{op}}$--$I$ characteristics of VM-LEDs and regular LEDs. The inset shows the $m$--$I$ characteristic of VM-LEDs and regular LEDs ($L_{\text{op}} \propto I^{m}$). |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.49.04DG10 |