Correlation of Threading Dislocations with the Electron Concentration and Mobility in InN Heteroepitaxial Layers Grown by MBE

Abstract

The quantitative interdependencies of growth conditions, crystal defects and electrical/electronic properties of InN thin films, grown by plasma-assisted molecular beam epitaxy on GaN (0001) buffer layers have been investigated. InN epilayers with thickness near 700 nm, grown under different substrate temperature and/or growth rate, have been analyzed. Bulk electron concentration (N bulk ) and mobility values were extracted for each InN film using the inverted version of the multilayer Petritz model, subtracting the conductivity of a corresponding 120 nm InN film. The results indicate a significant reduction of the threading dislocation density by enhancing the diffusion length of indium adatoms during InN growth, through increase of substrate temperature and reduction of growth rate. The electrical characteristics deteriorate with increasing threading dislocation density. Assuming threading dislocations as exclusive sources of donors in InN, their charge state could be between +1 and +2 per c lattice constant length of dislocation line for N bulk ≈ 4.0-5.7×10 17 cm −3 , and approximately +2 or larger for N bulk ≈ 1.5-1.8×10 18 cm −3 . The scattering effect of threading dislocations is significantly weaker compared to reported theoretical calculations, i.e. it would correspond to an order of magnitude lower threading dislocation density than the experimentally observed density in the range of 10 10 cm −2 .

Growth and Properties of N‐Polar InN/InAlN Heterostructures

“…Normally, InN relaxes immediately if grown on a highly lattice‐mismatched layer such as GaN, [ 2 ] creating dislocations and a low‐mobility region within the first ≈100 nm above the interface. [ 3 ] As a result, the InN thickness must be increased, which hinders its application in transistor structures. Only recently Lund et al demonstrated a decent mobility of 706 cm 2 V −1 s −1 in InN as thin as 20 nm.…”

Correlation of Morphology Evolution with Carrier Dynamics in InN Films Heteroepitaxially Grown by MOMBE

“…In addition, the In pellet is used as an ohmic contact. The purity of the pellet is 99.99%, and the diameter of the pellet is about 1 mm [13,14]. The InN nanorods have a lower carrier concentration and mobility than the InN films, which is due to the comparatively greater crystalline quality and 1D structure of the InN nanorods.…”

“…As with other III-V nitrides, bulk InN also lacks a native substrate. Fortunately, the nanometer-scale quasi-one-dimensional (quasi-1D) structure has become a subject of intense research interest due to the low structural defect density [13,14]. This nanostructure shows promising potential for the realization of both fundamental physical research and the improvement of electronic, optoelectronic, and chemical/biological sensing properties with nanodevices.…”

In(Ga)N 3D Growth on GaN-Buffered On-Axis and Off-Axis (0001) Sapphire Substrates by MOCVD

“…Recent advances in the epitaxial growth of indium nitride layers led to the correction of the optical InN bandgap to 0.65 eV (previously expected to be 1.9 eV) [1,2] and opened new horizons for InN-based photonic and electronic devices. They include light-emitting diodes (LEDs) and optical cells capable of light emission in the whole visible spectrum, InN-based lasers for 1.55 µm fiber optics, devices for THz spectroscopy, and high-speed transistors [3,4].…”