Band Gap Of Indium Nitride Research Articles

Influence of sputtering power and Ar–N2 flow on the structure and optical properties of indium nitride films prepared by magnetron sputtering

ABSTRACTThis paper discusses the deposition of indium nitride (InN) thin films on Si (100) substrates by using pulsed DC magnetron sputtering. Effects of varying sputtering power and Ar–N2 flow ratio on the structural, morphological, and optical properties of indium nitride (InN) films were investigated. The structural characterization indicated nanocrystalline InN film with preferred orientation towards (101) plane that exhibited the optimum crystalline quality at 130 W and for 40:60 Ar–N2 ratio. The surface morphology of InN, as observed through FESEM, contained irregularly shaped nanocrystals with size that increases with higher sputtering power and Ar:N2 flow ratio. The optical properties of InN films were studied using ellipsometer at room temperature. The band gap of InN was decreased with the increase of sputtering power to 130 W, whereas an increase in the band gap was noticed with the increase of the Ar:N2 flow ratio.

Optical properties of InN films grown by MOCVD

By means of optical absorption, photoluminescence (PL), Raman scattering and ellipsometry, optical properties of indium nitride (InN) films grown by metal organic chemical vapor deposition (MOCVD) are investigated. Through absorption and PL measurements, it is proven that the band gap of high quality InN is 0.68 eV, which agrees with the recently reported value, 0.7 eV. By analysis of the Raman scattering spectrum, the comparatively low background concentration of electron results in a smaller band gap value. The transition energy of wurtzite InN at critical point is determined by ellipsometric spectra. In addition, the complex refractive index of InN at energy ranging from 0.65 to 4.0 eV is obtained for the first time.

Characterizations of InN films on Si(111) substrate grown by metal-organic chemical vapor deposition with a predeposited In layer and a two-step growth method

In this study, a two-step growth method with a thin predeposited indium (In) layer is reported to grow high-quality indium nitride (InN) films on silicon (Si) substrates by metal-organic chemical vapor deposition. The surface morphologies of the InN films exhibited good surface quality as determined by scanning electron microscope and atomic force microscope. The wurtizite structure with lattice constants c=5.69Å and a=3.44Å of the InN films was observed by high-resolution transmission electron microscopy. A 540arcsec full width at half maximum of InN(0002) diffraction peak and a 0.756eV room-temperature interband transition energy of the InN films were also observed from x-ray diffraction and photoluminescence spectroscopy, respectively. A small temperature coefficient of ∼0.036meV∕K for the band gap of InN was determined. Such a small value could be explained by the small lattice mismatch and thermal expansion of InN on the Si substrate.

Critical point transitions of wurtzite indium nitride

The optical transmission, photoluminescence, and reflection spectra have been measured on a high-quality wurtzite indium nitride (InN) single crystal in the range of 0.5–20.0 eV. The fundamental bandgap of intrinsic InN has been extracted by taking into account the Burstein–Moss shift, bandgap renormalization and Urbach band tail effects, and found to be very close to the recent strongly re-established value of ∼1.2 eV. With the aid of Adachi's dielectric function model for the vacuum ultraviolet reflection spectra and the empirical pseudopotential method approach for the electron band-structure, we are able to identify up to nine electronic transitions, showing clear picture for the critical point transitions in InN. The temperature dependence of these interband transitions has also been revealed.

The influence of structural properties on conductivity and luminescence of MBE grown InN

Within the last few years indium nitride (InN) gained substantial interest due to its controversially discussed apparent band gap and its predicted highest maximum electron mobility among several III–V compounds, including Al(Ga)N and GaAs. The band gap of epitaxial InN has been recently reported to be around 0.7 eV rather than the previously accepted value of 1.9 eV obtained from polycrystalline films. Thus, InN could be a promising material for applications in infrared opto-electronics or high-speed electronics. However, the structural quality of the InN epilayers is still inferior to GaN and needs to be improved. Also, the role of many contaminants in InN and their effect on the epilayer's conductivity and/or luminescence properties is still under investigation. This work describes recent studies of InN growth by molecular beam epitaxy on sapphire (0 0 0 1) substrates. The effect of buffer layer variations including a prior substrate nitridation step is discussed. Structural properties (X-ray diffraction, AFM and TEM images) and chemical profiles (SIMS) will be correlated to Hall data and Photo-luminescence spectra. The role of oxygen and hydrogen as possible donors in InN will be discussed.

Absorption and Raman scattering processes in InN films and dots

We demonstrate that the phonon frequencies that are reported in the literature for indium nitride (InN), films are all consistently correlated to the strain state of the material. Raman spectroscopy measurements and X-ray investigations of large size InN quantum dots grown on c-plane GaN are combined, which show these frequencies to experience a blue shift with increasing compression. The InN dots are weakly strained, most probably due to the formation of dislocations at the InN/GaN interface. We report the observation of a broad absorption in the 1.25 eV region that is typical of thin InN films. Such a feature we attribute to light absorption at the energy of the fundamental direct band gap of InN, while we attribute the low energy 650–800 meV photoluminescence to an extrinsic recombination process analogous to the processes that produce the blue band in AlN and the yellow band in GaN.

Indium nitride (InN): A review on growth, characterization, and properties

During the last few years the interest in the indium nitride (InN) semiconductor has been remarkable. There have been significant improvements in the growth of InN films. High quality single crystalline InN film with two-dimensional growth and high growth rate are now routinely obtained. The background carrier concentration and Hall mobility have also improved. Observation of strong photoluminescence near the band edge is reported very recently, leading to conflicts concerning the exact band gap of InN. Attempts have also been made on the deposition of InN based heterostructures for the fabrication of InN based electronic devices. Preliminary evidence of two-dimensional electron gas accumulation in the InN and studies on InN-based field-effect transistor structure are reported. In this article, the work accomplished in the InN research, from its evolution to till now, is reviewed. The In containing alloys or other nitrides (AlGaInN, GaN, AlN) are not discussed here. We mainly concentrate on the growth, characterization, and recent developments in InN research. The most popular growth techniques, metalorganic vapor phase epitaxy and molecular beam epitaxy, are discussed in detail with their recent progress. Important phenomena in the epitaxial growth of InN as well as the problems remaining for future study are also discussed.

On the band gap of indium nitride

AbstractThe controversy about the band gap of indium nitride is discussed. It is shown by considering the electron effective mass in different direct‐gap II–VI and III–V semiconducting compounds that the controversy may be resolved by measuring the electron effective mass in indium antimonide samples showing a band gap of 0.7 eV.

A Study of Indium Nitride Films Grown Under Conditions Resulting in Apparent Band-gaps from 0.7 eV to 2.3 eV

ABSTRACTThe band-gap of indium nitride has long been believed to be about 1.9eV with slight variations due to band-tailing in polycrystalline samples and degenerate doping. Recently, other values as low as 0.7 eV have apparently been observed. We have compared samples spanning this apparent range of band-gap using secondary ion mass spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and heavy ion elastic recoil detection analysis (ERDA), in conjunction with spectral optical density measurements. Once structural inhomogeneiteies are taken into account, we show that much of the conflicting data are compatible with direct photoionisation with a threshold energy of about 1.0eV. This feature was first reported in polycrystalline indium nitride over 15 years ago and attributed to a ∣p> like defect state. We ask whether the feature may instead be a direct band-gap.

Optical band gap of indium nitride

Room-temperature optical absorption data in the 1.5–2.5-eV range are reported for indium nitride thin films prepared by reactive radio-frequency sputtering. The fundamental absorption edge in high-purity material is located at 1.89±0.01 eV and corresponds to a direct transition at k=0, in agreement with band-structure calculations. A significant Moss-Burstein shift is noted for carrier concentrations in excess of 1019 cm−3 and obeys the empirical relationship EG =1.89+2.1×10−8 n1/3 eV.