Noise investigation for thermionic field emission through well/barrier cells in multiquantum well avalanche photodiodes

6 page(s

High sensitivity, high resolution X-ray photoelectron analysis on InN

Only very few compositional surface and bulk studies of InN have been performed. It is known that there is a strong oxide presence on the surface of InN. We used a high sensitivity, high resolution X-ray photoelectron spectroscopy (XPS) system to study RF-sputtered and MBE grown InN samples. The energy resolution of the XPS system is such that the oxide and hydroxide contribution to the O1s peak can be easily resolved. 3 keV Ar ion milling was used to examine the bulk properties of the samples. The In3d5, N1s, C1s and O1s peaks were all examined for the samples studied. X-ray diffraction (XRD) and optical absorption measurements were also used to help characterize the sample surfaces and it is shown that the shifts in the lattice constant for degenerate material appears to be unrelated to oxygen content.5 page(s

Energy band gaps of InN containing oxygen and the InxAl1-xN interface layer formed during InN film growth

8 page(s

Absorption and photoluminescence features caused by defects in InN

10 page(s

Comparisons of gallium nitride and indium nitride properties after CF₄ / argon reactive ion etching

We present a comparative study of the effects of low power reactive ion etching (RIE) on GaN and InN. This new, highly chemical, dry etching, using CF4 and Ar, has been developed for thin nitride films grown at low temperature in our laboratories. GaN films were grown by remote plasma enhanced-laser induced chemical vapor deposition and InN films were grown by radio-frequency RF reactive sputtering. Commercial GaN samples were also examined. Optical and electrical characteristics of the films are reported before and after removing 100 to 200 nm of the film surface by RIE. We have previously shown that the GaN films, although polycrystalline after growth, may be re-crystallized below the growth temperature. Removal of the surface oxide has been found to be imperative since a polycrystalline residue remains on the surface after re-crystallization.6 page(s

Reliable ERD analysis of group-III nitrides despite severe nitrogen depletion

7 page(s

Optical and electronic properties of diatoms

The photoluminescence spectra and dielectric properties of diatoms, a biogenic source of porous silica, have been characterised. Results are compared with pure synthetic silica, and show low dielectric constants due to the porosity.1 page(s

Piezoelectricity in indium nitride

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Accurate stoichiometric analysis of polycrystalline indium nitride films with elastic recoil detection

Indium nitride thin films for potential application in high power, high frequency devices have been grown with reactive ion sputtering. Accurate film stoichiometries have been measured with elastic recoil detection using 200 MeV Au projectile ions. The beam-induced depletion of nitrogen during analysis has been found to be severe and non-linear with ion fluence. Assuming the formation of molecular nitrogen as the decisive step leading to nitrogen loss, a model has been applied which reproduces the experimental data. The model allows accurate extrapolations of the original nitrogen content of the material. All films studied have been found to be nitrogen-rich and have large band gaps ranging from 2.14 to 2.3 eV. The amount of excess nitrogen correlates with the band gap energy suggesting a Moss-Burstein effect. The excess nitrogen may thus act as donor and account for the high charge carrier concentrations of up to 2 × 1020 cm-3. The magnitude of the nitrogen excess is consistent with a donor level 50 meV below the conduction band

Piezoelectric coefficient of InN films prepared by radio-frequency sputtering

An interferometric method has been used to measure the piezoelectric coefficient d33 in indium nitride films deposited by radio-frequency sputtering on borosilicate glass coated with gold. This low temperature growth technique has the advantage of being able to produce samples for piezoelectric measurements where the InN film is grown directly on an Au metal back contact, allowing the accurate measurement of the piezoelectric coefficient of the InN layer without any parasitic series resistance. The InN growth conditions are described, and both crystal and optical characterizations of the film are presented. The measured value of the coefficient was found to be 4.0 ± 0.1 pm V⁻¹.4 page(s