Features of InN growth by nitrogen-plasma-assisted MBE at different ratios of fluxes of group-III and -V elements

Electron Accumulation Tuning by Surface-to-Volume Scaling of Nanostructured InN Grown on GaN(001) for Narrow-Bandgap Optoelectronics

“…19,20 InN nanocrystals have been reported to agglomerate in the form of high surface-to-volume ratio 3D structures, before coalescing into a film. 21,22 As a consequence, the presence of structural defects originated during the aggregates' coalition enriches the population of unintentional free carriers, as reported for InN in the form of nanowires, 23 nanocolumns, 24 and films, 25 reaching orders of magnitude close to 10 20 cm −3 . One important obstacle faced when analyzing the electron concentration of segregated nanomaterials is the difficulty in establishing a direct contact to investigate carrier properties using electrical methods, such as Hall measurements.…”

“…Many of the structural properties defined during InN growth sensitively determine the device operation. , The most difficult growth challenges result from the high lattice mismatch of ∼11% between InN ( a InN ≈ 3.545 Å) and the GaN (0001) ( a GaN ≈ 3.189 Å) substrates on which it is usually grown. This can easily result in the formation of disordered nanocrystals instead of 2D films. , InN nanocrystals have been reported to agglomerate in the form of high surface-to-volume ratio 3D structures, before coalescing into a film. , As a consequence, the presence of structural defects originated during the aggregates’ coalition enriches the population of unintentional free carriers, as reported for InN in the form of nanowires, nanocolumns, and films, reaching orders of magnitude close to 10 20 cm –3 .…”

“…In the case of PL experiments, it should be noted that besides the lifetime-limited spectral linewidth, the optical transitions of low-dimensional materials with low quality and rich mosaicity have displayed luminescent emissions related to morphological- and impurity-related effects, which contribute to an inhomogeneous PL broadening that must be considered in the spectral analysis and consequently affects the reliable determination of the electron concentration . Only a few reports have been published addressing quantitatively the influence of surface irregularities on the electrical properties of InN structures …”

“…Particularly, for InN epilayers grown by molecular beam epitaxy (MBE), it has been reported that an over-stoichiometric In/N flux ratio increases the electron population and reduces the electron mobility . Morphologically, the beginning of a transition between three- and two-dimensional structures has been observed for In/N flux ratios in the range of 0.6–0.9, where the nitrogen-rich atmosphere leads to the formation of free-standing nanocolumns, while an indium-rich atmosphere favors the growth of a continuous film . In the case of PL experiments, it should be noted that besides the lifetime-limited spectral linewidth, the optical transitions of low-dimensional materials with low quality and rich mosaicity have displayed luminescent emissions related to morphological- and impurity-related effects, which contribute to an inhomogeneous PL broadening that must be considered in the spectral analysis and consequently affects the reliable determination of the electron concentration .…”

Towards the indium nitride laser: obtaining infrared stimulated emission from planar monocrystalline InN structures

“…In order to obtain stimulated emission and to study the conditions for its realization in the planar InN layers, a series of monocrystalline InN samples were grown by plasma-assisted molecular-beam epitaxy (PA MBE) on (0001) sapphire substrates. The details of the growth procedure can be found in the Method section, supplementary materials and elsewhere 24 . To expand the range of the parameters of InN structures that affect the implementation and characteristics of stimulated emission, we have also studied the structures grown earlier at Cornell University.…”