Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

Abstract

The effect of patterned sapphire substrate (PSS) on the top-surface (P-GaN-surface) and the bottom-surface (sapphire-surface) of the light output power (LOP) of GaN-based LEDs was investigated, in order to study the changes in reflection and transmission of the GaN-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of GaN-based LEDs, which are prepared on patterned sapphire substrates (PSS-LEDs). Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates (CSS-LEDs). A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-GaN interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency (LEE) can be further enhanced by integrating the method of PSS and flip-chip structure design.

Influence of carrier gas H 2 flow rate on quality of p-type GaN epilayer grown and annealed at lower temperatures

“…In recent years, gallium nitride (GaN) and its ternary alloys have attracted a great deal of attention thanks to their material properties, which are advantageous for applications in light emitters and detectors devices. [1][2][3][4][5] Nevertheless, the quality of p-type GaN sometimes still acts as a bottleneck that limits the performance of these devices. [6] Up to now, Mg, as a singly useful element, has been used to dope p-type GaN.…”

Uniform-Sized Indium Quantum Dots Grown on the Surface of an InGaN Epitaxial Layer by a Two-Step Cooling Process

“…Recent years, (Al, In, Ga)N-based materials have attracted a great deal of attention due to their successful application in a light-emitting device (LED) and laser diode (LD) [1][2][3][4][5]. InGaN has high absorption, broad spectral coverage, and radiation hardness and it is always used as an active material for the fabrication of optoelectronic devices.…”