Papers by Keyword: InN

Abstract: We have fabricated a new semiconducting material, (ZnO)_x(InN)_1-x (called ZION hereafter), which is a pseudo-binary alloy of wurtzite ZnO (band gap: 3.4 eV) and wurtzite InN (band gap: 0.7 eV). We have succeeded in fabricating epitaxial (ZnO)_0.82(InN)_0.18 films on ZnO templates by RF magnetron sputtering. XRD measurements show that the full width at half maximum of the rocking curves from (101) plane and (002) plane are significantly small of 0.11 ̊ and 0.16 ̊, respectively, indicating good in-plane and out-of-plane crystal alignment. High crystal quality of the films was also proved by deducing the defect density from XRD analysis showing that the edge type dislocation density is low of 8.2×10⁸ cm^-2. Furthermore, we observed room temperature photoluminescence from ZION films as a parameter of incident angle of He-Cd laser light. The results indicate that an emission peak of 2.79 eV is originated from ZION.

Abstract: We studied effects of sputtering pressure on growth of (ZnO)_x(InN)_1-x crystal films deposited at 450°C by rf magnetron sputtering. Epitaxial growth of (ZnO)_x(InN)_1-x films was realized on single-crystalline ZnO template. X-ray diffraction measurements show that full width at half maximum of the rocking curves from the (101) plane of the films reaches minimum value of 0.11º at 0.5 Pa. The sputtering gas pressure is a key tuning knob for controlling the crystal quality of ZION films.

Abstract: This paper focuses on the applicability of InN based quantum dot in the active layer of the solar cell to reduce the short circuit current variation above the room temperature. We have investigated numerically the effect of temperature on the short circuit current of the solar cell using InN based quantum dot in the active layer of the solar cell. The numerical results are compared with those obtained by using Ge based quantum dot. The comparison results revealed that the short circuit current has been increased slightly but the variation of short circuit current has been reduced significantly in the case of using InN quantum dot in the active layer of the device structure. As the results, InN can be considered as the best alternative material to fabricate solar cell with higher short circuit current in upcoming decades.

Abstract: The electronic properties and the optical properties of wurtzite InN are studied by the first-principles calculations based on the density functional theory. The calculations are based on the Generalized-Gradient Approximation (GGA) and implemented in Plane Wave Self-Consist Field (PWSCF). The optical properties of InN are investigated by the pseudo-potential method with PBEsol-GGA within the WIEN2K program. Band structure, density of states and dielectric functions are calculated detailedly. The energy transitions are observed and compared existing data at critical points. Moreover the new peak in between the region 12 eV to 14 eV should be due to transitions from the In-5p states to the N-2s states.

Abstract: Retracted paper: The conventional material for the optical fiber communication laser diode is based on InGaAsP, which might be substituted by a potential candidate, InGaAlN. The new active region material, InN, is introduced regarding to its crystal growth and characterization, including the structural, optical and electrical properties. This material is promising for providing good performance of temperature stability of the wavelength. In addition, it is environmentally friendly.

Abstract: This paper reports the improvement of open circuit voltage stability of solar cell using InN based quantum dot in the active layer of the device structure. We have analyzed theoretically the temperature dependence of the open circuit voltage of the solar cell to investigate its fluctuation using Ge and InN based quantum dot in the active layer of the solar cell. Numerical results obtained are compared. The comparison results reveal that the open circuit voltage has been reduced a little bit but the fluctuation of terminal voltage has been reduced significantly by using InN quantum dot in the active layer of the device structure. Therefore InN is proved to be an excellent material to fabricate solar cell to provide higher stability in the open circuit voltage of the solar cell in very near future.

Abstract: We report the effects surface treatment and annealing had on the properties of InN layers grown using metal organic chemical vapor deposition (MOCVD). The number of defects due to N vacancies decreased significantly with increasing annealing temperature. However, when the annealing temperature reached 700°C, the crystalline grain became larger on the film surfaces. Annealing at an appropriate temperature improved the crystalline quality and the electrical properties of the InN films. However, when the annealing temperature was too high, InN oxidized and even dissociated.

Abstract: Reduction in threshold current density is the major challenge in the field of semiconductor laser design. The threshold current density can be minimized by introducing low dimensional material system with narrow band gap. InN has a narrow band gap of 0.7 eV and quantum dot provides three dimensional confinement factor. In this paper, we propose then InN quantum dot as the active layer material that will serve both the purpose of narrow band gap and three dimensional confinement. The simulation results show that the current density reduces drastically with the cavity length.

Abstract: We have studied the effects of deposition conditions on the crystal structure of InN films deposited on Si substrate. InN thin films have been deposited on Si(100) substrates by reactive radio frequency (RF) magnetron sputtering method with pure In target at room temperature. The nitrogen gas pressure, applied RF power and the distance between target and substrate were 2×10^-2 Torr, 60 W and 8 cm, respectively. The effects of the Ar–N2 sputtering gas mixture on the structural properties of the films were investigated by using scanning electron microscope, energy-dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction techniques.

Abstract: An InN film was grown on sapphire (c-plane) by plasma-assisted molecular beam epitaxy, and its photoluminescence at 10 K and photoreflectance (PR) spectra from 10 K to 110 K were measured. Some prominent features in the PR spectra were observed in the infrared region below 120 K. The signals become too weak to observable for temperature above 110K. Furthermore, the binding energy of InN exciton was estimated to be 9.43 meV, which is equal to kBT at 109K. Therefore, the features in the PR spectra were assigned to the A, B, and C excitonic transitions associated with the direct gap of wurtzite InN. The thus obtained energies of the A, B, and C excitonic transitions versus temperature were fitted well by Varshini’s equation. The energies of the A, B, and C excitonic transitions at room temperature obtained by the best fit of Varshni’s equation are 0.738, 0.746, and 0.764 eV, respectively.