Dayi Liu

High density GaN/AlN quantum dots for deep UV LED with high quantum efficiency and temperature stability

High internal efficiency and high temperature stability ultraviolet (UV) light-emitting diodes (LEDs) at 308 nm were achieved using high density (2.5 × 109 cm−2) GaN/AlN quantum dots (QDs) grown by MOVPE. Photoluminescence shows the characteristic behaviors of QDs: nearly constant linewidth and emission energy, and linear dependence of the intensity with varying excitation power. More significantly, the radiative recombination was found to dominant from 15 to 300 K, with a high internal quantum efficiency of 62% even at room temperature.

Enhancement of p-type conductivity by modifying the internal electric field in Mg- and Si-δ-codoped AlxGa1-xN /AlyGa1-yN superlattices

National Natural Science Foundation [60827004, 60776066, 90921002]; Science and Technology program of Fujian and Xiamen of China

Enhanced Pockels effect in GaN∕AlxGa1−xN superlattice measured by polarization-maintaining fiber Mach-Zehnder interferometer

Six-period 4 nm GaN/10 nm AlxGa1-xN superlattices with different Al mole fractions x were prepared on (0001) sapphire substrates by low-temperature metal-organic chemical vapor deposition. The linear electro-optic (Pockels) effect was studied by a polarization-maintaining fiber-optical Mach-Zehnder interferometer system with an incident light wavelength of 1.55 mu m. The measured electro-optic coefficients, gamma(13)=5.60 +/- 0.18 pm/V, gamma(33)=19.24 +/- 1.21 pm/V (for sample 1, x=0.3), and gamma(13)=3.09 +/- 0.48 pm/V, gamma(33)=8.94 +/- 0.36 pm/V (for sample 2, x=0.1), respectively, are about ten times larger than those of GaN bulk material. The enhancement effect in GaN/AlxGa1-xN superlattice can be attributed to the large built-in field at the interfaces, depending on the mole fraction of Al

Origins and suppressions of parasitic emissions in ultraviolet light-emitting diode structures

863 program; National Nature Science Foundation [60827004, 90921002, 60776066]; Science & Technology Program of Fujian and Xiamen of China

Pockels effect in GaN/AlxGa1-xN superlattice with different quantum structures

The linear electro-optic (Pockels) effect of wurtzite gallium nitride (GaN) films and six-period GaN/AlxGa1-xN superlattices with different quantum structures were demonstrated by a polarization-maintaining fiber-optical Mach-Zehnder interferometer system with an incident light wavelength of 1.55μm. The samples were prepared on (0001) sapphire substrate by low-temperature metalorganic chemical vapor deposition (MOCVD). The measured coefficients of the GaN/AlxGa1-xN superlattices are much larger than those of bulk material. Taking advantage of the strong field localization due to resonances, GaN/AlxGa1-xN SL can be proposed to engineer the nonlinear responses.