Crack-free InGaN multiple quantum wells light-emitting diodes structures transferred from Si (111) substrate onto electroplating copper submount with embedded electrodes

Abstract

Crack-free InGaN multiple quantum wells (MQWs) light-emitting diodes with embedded electrode structures (EE-LEDs) were transferred from Si (111) substrate onto the electroplating copper submount. Crystalline quality was investigated by the high resolution x-ray diffraction (HR-XRD) measurement, in which no obvious deteriorations were found in the MQWs structure after the LEDs transferred from silicon substrate onto copper except for a partial residual strain relaxation in the film. The strain relaxation after silicon removal leads to a reduction in quantum confined stark effect (QCSE), which results in the enhancement of internal quantum efficiency (IQE). In comparison to the conventional LEDs on silicon substrate, the light output of the EE-LEDs on copper was enhanced by 122% at an injection current of 350 mA. Besides the enhancement of IQE, the improvement is also attributed to the following factors: the removal of the absorptive substrate, the inserting of the metal reflector between the EE-LEDs structure and the copper submount, the elimination of the electrode-shading, and the rough surface of the exposed AlN buffer layer.

Performance improvement of GaN-based light-emitting diodes transferred from Si (111) substrate onto electroplating Cu submount with embedded wide p-electrodes

“…[31] In addition, DBRs are usually applied in conventional p-side-up LEDs, which cannot eliminate the shadow effect by p-electrodes. [32] Therefore, the Si substrate transferring technique [33][34][35][36][37][38][39][40] is mainly adopted to eliminate the absorption of Si substrates and shadow effect, by inserting a metallic reflector. For instance, in our previous work, [40] we presented the embedded electrode LEDs (EE-LEDs) transferred from Si substrate onto Cu submount, which enhances the light output by 122%.…”

“…[32] Therefore, the Si substrate transferring technique [33][34][35][36][37][38][39][40] is mainly adopted to eliminate the absorption of Si substrates and shadow effect, by inserting a metallic reflector. For instance, in our previous work, [40] we presented the embedded electrode LEDs (EE-LEDs) transferred from Si substrate onto Cu submount, which enhances the light output by 122%. However, since the p-electrode is much narrower than the TCL and the thin TCL presents lateral resistance, it leads to current crowding near the p-electrode, [40,41] which would also aggravates the shadow effect in the conventional p-side-up LEDs.…”

“…For instance, in our previous work, [40] we presented the embedded electrode LEDs (EE-LEDs) transferred from Si substrate onto Cu submount, which enhances the light output by 122%. However, since the p-electrode is much narrower than the TCL and the thin TCL presents lateral resistance, it leads to current crowding near the p-electrode, [40,41] which would also aggravates the shadow effect in the conventional p-side-up LEDs. This current crowding adversely affects the uniformity and stability of the light emission.…”

Effect of Same‐Temperature GaN Cap Layer on the InGaN/GaN Multiquantum Well of Green Light‐Emitting Diode on Silicon Substrate

“…Therefore, silicon is used by some researchers as substrate to grow GaN-based LEDs and reduce device cost for its low cost, availability of large size, high surface quality, high conductivity, and well-established processing techniques [ 3 – 5 ]. Today GaN blue LEDs have already been grown on silicon substrate by several groups, which provide one of the low-cost solutions for solid state lighting [ 6 – 8 ].…”

Vertical-conducting InGaN/GaN multiple quantum wells LEDs with AlN/GaN distributed Bragg reflectors on Si(111) substrate

“…Although GaN-based LEDs on Si substrates have been extensively studied, volume production remains difficult mainly owing to the stress problem between GaN and Si substrates and optical absorption by opaque Si substrates. 1) In order to improve the light efficiency of LEDs on Si substrates, the silicon substrate transferring technique [2][3][4][5][6][7][8][9][10] is mainly adopted to eliminate optical absorption by Si substrates. However, the substrate transferring technique induces a complicated process and results in low yield and high cost.…”