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The thermal oxidation rates of Al0.83In0.17N layers grown lattice-matched to GaN and the oxide's optical constants are studied. The ∼230 nm thick AlInN layers are placed into a horizontal furnace at elevated temperatures and exposed to either O2 (dry) or H2O vapor with an N2 carrier gas (wet). The samples are oxidized at different temperatures (830–870 °C) and at a constant time or at various times at a constant temperature of 830 °C. Spectroscopic ellipsometry is used to determine the oxide thicknesses, refractive index, and extinction coefficients. The oxidation rate for the wet conditions is faster than for the dry conditions, and both increase with temperature, as expected. However, the oxidation rate is also dynamic with time and can be fitted with the Deal–Grove model, suggesting reaction rate and diffusion-limited processes like other more mature semiconductors. Finally, the dry conditions produce oxides that expand more than the oxides produced under wet conditions. The ability to thermally oxidize Al0.83In0.17N layers lattice-matched to GaN is a promising process technique for producing new III-nitride-based electronic devices. [ABSTRACT FROM AUTHOR]

The dilute-As InyGa1 − yN1 − xAsx alloys are explored by performing first-principles density functional theory (DFT) calculations, where the In-content is varied from 0% up to 18.75% and the As-content is varied from 0% up to 3.13%. The obtained band structures indicate a direct bandgap semiconductor, whose electronic properties are modified significantly by the addition of As-atoms into the InGaN-based system. The lattice parameters (a and c) are analyzed, and the bowing parameters of the dilute-As InGaNAs are analyzed and discussed. The electronic properties indicate the dilute-As InyGa1 − yN1 − xAsx alloys as a potential new material alternative for achieving longer wavelength emission, while utilizing a low In-content (<20%). [ABSTRACT FROM AUTHOR]

The recombination rates in InGaN/AlGaN/GaN multiple quantum wells (MQWs) emitting in the green-yellow and grown with different Al compositions in the AlGaN interlayer (IL) are shown. By transforming measurements on radiative efficiency, absorption, and differential carrier lifetime, the radiative and nonradiative rates are determined. The IL Al composition controls lattice relaxation of the MQWs, as determined by X-ray reciprocal space mapping, and, therefore, defect formation. For the most pseudomorphic MQWs, the Shockley-Read-Hall (SRH) A coefficient is minimized and is similar to reports at shorter (blue and green) wavelengths. It is an order of magnitude smaller than a conventional InGaN/GaN MQW and is the most significant factor behind the improvement in radiative efficiency using the IL. The radiative B coefficient is also reduced and a minimum for the most pseudomorphic MQWs due to a reduction in the electron-hole wavefunction overlap. However, the decrease in A is more significant and leads to an overall improvement in the radiative efficiency. These recombination rate measurements confirm that if the SRH recombination is controlled, then the severe reduction of radiative recombination with an increased emitting wavelength is one of the main challenges in realizing high efficiency, long-wavelength InGaN-based MQW emitters operating at low to moderate current densities. [ABSTRACT FROM AUTHOR]

The recombination rates in an In0.25Ga0.75N/Al0.48Ga0.52N/GaN multiple quantum well (MQW) structure are measured to identify the cause of low efficiencies in high In-content InGaN quantum wells. The MQWs emit from 640 to 565 nm and are grown using metal-organic chemical vapor deposition (MOCVD). The addition of AlGaN interlayers within the MQW provides strain balancing and suppresses defect formation in high In-content InGaN quantum wells. The rates are found by transforming the optically measured radiative efficiency, differential carrier lifetimes, and optical absorption. Both components of non-radiative recombination rates, Shockley-Read-Hall (SRH) and Auger recombination, are found to be similar to the values of blue-emitting InGaN MQWs. The low SRH recombination rate is attributed to the use of the AlGaN interlayer. The radiative recombination rate, however, is more than an order of magnitude lower compared to blue emitting (lower In-content) InGaN-based MQWs. While this large reduction in radiative rate can be attributed to differences in carrier overlap and transition energy, it may also include effects of variations in thickness and compositional inhomogeneities. [ABSTRACT FROM AUTHOR]

An investigation on the optical properties of dilute-P GaN 1-x P x alloys by First-Principle Density Functional Theory (DFT) methods is presented, for phosphorus (P) content varying from 0% up to 12.5%. Findings on the imaginary and real part of the dielectric function are analyzed and the results are compared with previously reported theoretical works on GaN. The complex refractive index, normal-incidence reflectivity and birefringence are presented and a difference in the refractive index in the visible regime between GaN and GaNP alloys of ~0.3 can be engineered by adding minute amounts of phosphorus, indicating strong potential for refractive index tunability. The optical properties of the GaN 1-x P x alloys indicate their strong potential for implementation in various III-nitride-based photonic waveguide applications and Distributed Bragg Reflectors (DBR).

A study on the electronic properties of the dilute-P GaN(1-x)P(x)alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications.