Yellow-red light-emitting diodes using periodic Ga-flow interruption during deposition of InGaN well

Abstract

We report a possible way to extend the emission wavelength of InyGayN/InxGaxN quantum-well (QW) light-emitting diodes (LEDs) to the yellow-red spectral range with little degradation of the radiative efficiency. The InyGayN well with high indium (In) content (HI-InyGayN) was realized by periodic Ga-flow interruption (Ga-FI). The In contents of the HI-InyGayN well and the InxGaxN barrier were changed to manipulate the emission wavelength of the LEDs. An InGaN/InGaN-QW LED, grown by continuous growth mode (C-LED), was prepared as a reference. The photoluminescence (PL) wavelengths of the HI-InyGayN/InxGaxN QW LEDs were changed from 556 to 597 nm. The PL intensity of the HI-InyGayN/InxGaxN LED with a peak wavelength of 563 nm was 2.7 times stronger than that of the C-LED (λ = 565 nm). The luminescence intensity for the HI-InyGayN/InxGaxN QW LED emitting at 597 nm was stronger than those of the other LED samples with shorter wavelengths. Considering the previous works on degradation in crystal quality and increase in the quantum-confined Stark effect with increasing In content in InGaN, the approach in this work is very promising for yellow-red InGaN LEDs.

The effect of nanometre-scale V-pits on electronic and optical properties and efficiency droop of GaN-based green light-emitting diodes

“…A second issue related to obtaining high-efficiency green LEDs is the strong polarization effects that arise from their wurtzite crystal structure. In particular, piezoelectric and spontaneous polarization effects generate strong internal electric fields in the InGaN/GaN multiple quantum well (MQW), leading to a spatial separation of the electron and hole wave functions in the quantum wells (QWs) and, thus, a reduction in the radiative recombination rates 22 , 23 .…”

Application of Hexagonal Boron Nitride to a Heat-Transfer Medium of an InGaN/GaN Quantum-Well Green LED

“…The InGaN/GaN QWs consisted of five periods with 3 nm thick InGaN well layers and 9 nm thick GaN barriers. Si-doped 12-period InGaN/GaN graded superlattice structures fabricated by carrying out a so-called In-conversion technique were inserted below the active QW layer . The LEDs were fabricated by using a standard process with a die size of 1000 × 1000 μm 2 .…”

“…Indium-tin-oxide with a thickness of 150 nm was deposited as a transparent conducting layer on the p-GaN cladding layer, and Cr/Au was deposited as the n- and p-type electrodes, respectively. The growth conditions and structural properties of InGaN/GaN-QW LEDs are described in detail in our previous reports. − …”

“…Si-doped 12-period InGaN/ GaN graded superlattice structures fabricated by carrying out a socalled In-conversion technique were inserted below the active QW layer. 29 The LEDs were fabricated by using a standard process with a die size of 1000 × 1000 μm 2 . Indium-tin-oxide with a thickness of 150 nm was deposited as a transparent conducting layer on the p-GaN cladding layer, and Cr/Au was deposited as the n-and p-type electrodes, respectively.…”