Low-temperature InN Buffer Layer Research Articles

Effects of substrate nitridation and buffer layer on the crystalline improvements of semi-polar InN(101¯3) crystal on GaAs(110) by MOVPE

In this report, effects of ammonia nitridation and low temperature InN buffer growth were investigated to improve the crystalline quality of InN(101¯3) grown on GaAs(110) by metalorganic vapor phase epitaxy (MOVPE). InN(101¯3) single crystal including less than 0.1% of differently oriented domains was successfully grown by inserting low temperature InN buffer layer. The full width at half maximum (FWHM) values of InN(101¯3) epitaxial layer were drastically decreased from 89arcmin to 55arcmin after processing ammonia nitridation of GaAs(110) substrate surface. Furthermore, the FWHM value was decreased to 38arcmin by increasing growth time, and the mechanism of dislocation annihilation happened during epitaxial growth was discussed.

The growth and properties of an m-plane InN epilayer on LiAlO2 (100) by metal-organic chemical vapor deposition

The m-plane InN (1 \(\bar 1\) 00) epilayers have been grown on a LiAlO2 (1 0 0) substrate by a two-step growth method using a metal-organic chemical vapor deposition (MOCVD) system. The low temperature InN buffer layer (LT-InN) is introduced to overcome the drawbacks of thermal instability of LiAlO2 (LAO) and to relieve the strains due to a large thermal mismatch between LAO and InN. Then the high temperature m-plane InN (1 \(\bar 1\) 00) epilayers (HT-InN) were grown. The results of X-ray diffraction (XRD) suggest that the m-plane InN (1 \(\bar 1\) 00) epilayer is a single crystal. The X-ray rocking curves (ω scans) (XRC) and atomic force microscopy (AFM) indicate that the m-plane InN (1 \(\bar 1\) 00) epilayer has anisotropic crystallographic properties. The PL studies of the materials reveal a remarkable energy band gap structure around 0.70 eV at 15 K.

The influence of the LT-InN buffer growth conditions on the quality of InN films grown on Si(1 1 1) substrate by MBE

This work aims to explore the effect of the growth conditions of low-temperature InN (LT-InN) buffer layers on the quality of wurtzite InN films grown on Si(1 1 1) substrates by plasma-assisted molecular beam epitaxy (PA-MBE). Experimental results indicated that higher growth rate and lower thickness of LT-InN buffer layer guarantee better crystalline quality and optical properties for InN films grown at the same temperature. The crystalline quality of the InN epilayers was investigated by high-resolution X-ray diffraction (XRD) performed on the reflection plans of various inclination angles. XRD study confirmed that the dominating threading dislocation was edge type. Surface morphology was measured by atomic force microscope (AFM), and optical property was characterized by photoluminescence (PL). The best InN film was obtained from the sample with a 20 nm LT-InN buffer layer, 140 nm/h growth rate, and 500 °C HT-InN growth temperature. The characterization results showed 2.785×10 10 cm –2 edge-type dislocation density estimated by XRD, 11.57 nm AFM RMS roughness, and 0.666 eV near band-edge PL transition at 15 K with 24 meV broadening.

Crystal growth of InN by MOCVD with electric field along the c-axis

We report on physical properties of InN grown by metalorganic chemical vapor deposition (MOCVD) with electric field applied along the c-axis. The electric field is applied continuously from the growth of the low temperature InN buffer layer to the procedure of cooling down to room temperature. As a result, the crystal morphology degrades, c-lattice constant elongates by 0.12% at ±1 kV/cm, Hall mobility decreases, and the phonon vibration along the c-axis broadens, which suggests that the physical properties of InN can be controlled by the electric field applied along the c-axis during the crystal growth.

Structural characterization of InN films grown on different buffer layers by metalorganic chemical vapor deposition

InN films were grown on sapphire substrate by metalorganic chemical vapor deposition (MOCVD). Different buffer layers were used to investigate their effects on structural properties of InN films. These buffers include the nitrided treatment to the sapphire substrate, a low-temperature InN buffer layer and a thick GaN template. Symmetric high resolution X-ray diffraction (HRXRD) ω/2 θ scans and asymmetric (1 0 1¯ 2) Φ scans confirmed all these InN films had a wurtzite-type structure and the in-plane orientation relationship between InN and Al 2O 3 was uniquely [ 1 0 1 ¯ 0 ] InN | | [ 1 1 2 ¯ 0 ] Al 2 O 3 . The full-width at half maximum (FWHM) of X-ray (0 0 0 2) rocking curve decreased from 2.44° to 1.09° by inserting a low-temperature InN buffer. The narrowest FWHM of 0.36° for (0 0 0 2) rocking curve was obtained for InN film grown on a thick GaN template, whose large lateral coherence length is about 311 nm. Atomic force microscopy (AFM) images revealed that InN films without GaN buffer had a root-mean-square (RMS) roughness of 20 nm while that with a GaN template had a RMS roughness of 80 nm. So, both the low-temperature InN buffer and GaN template can improve InN film features from different aspects. It is necessary to combine the two methods to improve the quality of InN film.

Growth of polycrystalline InN on silica glass by ECR‐MBE

InN films are grown on amorphous silica glass by electron cyclotron resonance plasma-excited molecular beam epitaxy. InN films grown directly on the substrate without a buffer layer are polycrystalline with no preferred growth orientation and a three-dimensional grainy morphology, whereas films grown on a low-temperature InN buffer layer are polycrystalline with uniform c-axis orientation and random a-axis orientation. Substrate nitridation prior to the growth is found to improve the surface morphology and uniformity of c-axis orientation, similar to the case for poly-GaN growth on silica glass. Notably, this poly-InN on silica glass exhibited room-temperature photoluminescence emission at ∼0.75 eV, with an optical absorption edge at almost the same position as the emission peak. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of the low temperature buffer and annealing on the properties of InN layers grown by MOVPE

AbstractInN thin films grown by MOVPE with a thickness of about 100 nm are investigated. Growth was carried out in either two or three steps: deposition of a low temperature nucleation layer at 400 °C and subse‐ quent growth of a thicker InN layer at 530 °C, or use of a GaN buffer layer which was annealed at 1050 °C prior to deposition of the low temperature InN buffer layer. The structural evolution of the layers during a 20 min annealing step at 540 °C under nitrogen was investigated using AFM and XRD. We analyzed the orientation distribution function of the layers by XRD reciprocal space maps applying ψ and χ scans. The results show that the crystalline layer quality is improved by use of a GaN buffer, as also assessed from higher photoluminescence intensity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Growth of high-quality InN films by insertion of high-temperature InN buffer layer

For the growth of further-improved InN film on a sapphire substrate, the effects of the conventional initial growth process, which is substrate nitridation and the deposition of a low-temperature InN buffer layer prior to growth, were carefully reinvestigated. Although the deposition of the low-temperature InN buffer layer realized a flat surface, the degradation of the crystallinity simultaneously resulted. The insertion of a high-temperature InN buffer layer solved this problem, and a high-quality InN film with a small tilt-distribution and a very flat surface was realized.

Structural Characterization of Low-Temperature InN Buffer Layer Grown by RF-MBE

ABSTRACTThe microstructure of an InN buffer layer grown on (0001) sapphire at low temperature by radio-frequency molecular beam epitaxy (RF-MBE) is characterized by transmission electron microscopy. The low-temperature InN buffer layer is found to contain local inhomogeneous regions of island-like grains surrounded by misoriented InN grains and inclusions of cubic phase. The generation of such anti-phase InN nuclei near the island-like grains is expected to give rise to defects at the interface. It is considered that these anti-phase InN nuclei are formed by local fluctuations of stoichiometry due to inadequate surface migration during the growth of the InN buffer layer, indicating the important of controlling the surface stoichiometry during InN growth.

High temperature growth of InN on GaP(1 1 1)B substrate using a new two-step growth method

High temperature growth of InN is studied on GaP(1 1 1)B substrate using a new two-step growth method by metal organic vapor phase epitaxy. A single crystalline InN film with an excellent surface morphology can be grown on GaP(1 1 1)B at high temperature (600–650°C) using a low temperature InN buffer layer. The low temperature InN buffer layer is grown at 450°C, and then the temperature is raised to the epitaxial growth temperature (600–650°C) while continuing the growth. It is found to be a very effective growth technique to obtain high temperature growth of InN using a low temperature buffer layer. The low temperature InN buffer layer was also needed to suppress the substrate surface nitridation during the growth at such high temperature. The differences of this new two-step growth method from the conventional two-step growth method as well as their influences on the grown InN films are also discussed in details.

A Novel Two-Step Method for Improvement of MOVPE Grown InN Film on GaP(111)B Substrate

This paper reports a novel two-step method for improvement of MOVPE grown InN film on GaP(111)B, which includes the growth of a low temperature InN buffer layer and a high temperature epilayer. The additional feature of this two-step method which distinguishes it from the commonly known two-step method is that after growing the low temperature InN buffer layer the temperature is raised to the epitaxial growth temperature while continuing the growth. It is found that a single crystalline InN film with an excellent surface morphology can be grown on GaP(111)B at high temperature (∼600 °C) by this novel two-step method. In contrast, InN film grown by the conventional two-step method is found to be very rough. Differences between these two growth techniques and their influences on the buffer layer and then on main epilayer are also discussed.