GaN Film Grown on Si Substrate for Monolithic Optical MEMS

2005 ◽  
Author(s):  
F.-R. Hu ◽  
K. Ochi ◽  
B.-S. Choi ◽  
Y. Kanamori ◽  
K. Hane
Keyword(s):  
Growth Conditions ◽  
Photonic Devices ◽  
Optical Systems ◽  
Si Substrate ◽  
Optical Mems ◽  
Light Emitting ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mems Technology ◽  
Gan Film

GaN is a new and powerful material for photonic devices such as light emitting and laser diodes. On the other hand, optical MEMS technology is attractive for miniaturizing several optical systems. We are studying GaN film grown on Si substrate for the optical MEMS application in order to fabricate monolithic structure. In this paper, the characteristics of GaN film grown on Si substrate by MBE are reported. The growth conditions of GaN layer on Si substrate are studied. The surface morphology of the grown GaN film is measured by electron microscopy and atomic force microscopy. Furthermore, a preliminary grating structure is fabricated for a MEMS application.

Drastic Change in the Gan Film Quality by In-Situ Controlling Surface Reconstructions In Gsmbe

1997 ◽  
Vol 482 ◽  
Author(s):  
X. Q. Shen ◽  
S. Tanaka ◽  
S. Iwai ◽  
Y. Aoyagi
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Gas Source ◽  
Atomic Force ◽  
Surface Reconstructions ◽  
Gan Film

AbstractGaN growth was performed on 6H-SiC (0001) substrates by gas-source molecular beam epitaxy (GSMBE), using ammonia (NH3) as a nitrogen source. Two kinds of reflection high-energy electron diffraction (RHEED) patterns, named (1×1) and (2×2), were observed during the GaN growth depending on the growth conditions. By careful RHEED study, it was verified that the (1×1) pattern was corresponded to a H2-related nitrogen-rich surface, while (2×2) pattern was resulted from a Ga-rich surface. By x-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) characterizations, it was found that the GaN quality changed drastically grown under different RHEED patterns. GaN film grown under the (1×1) RHEED pattern showed much better qualities than that grown under the (2×2) one.

scholarly journals Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films

2018 ◽  
Vol 5 (2) ◽  
pp. 171179 ◽  
Author(s):  
Bramaramba Gnapareddy ◽  
Sreekantha Reddy Dugasani ◽  
Junyoung Son ◽  
Sung Ha Park
Keyword(s):  
Thin Films ◽  
Photonic Devices ◽  
Uv Absorption ◽  
Optical Characteristics ◽  
Force Microscopy ◽  
Atomic Force ◽  
Functionalized Nanomaterials ◽  
Amorphous Structures ◽  
The Fourier Transform ◽  
Immense Potential

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF] C , approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF] C . [RF] C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF] C followed by an increase above [RF] C . By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices.

Studies of Nanomechanical Properties of Pulsed Laser Deposited NbN films on Si Using Nanoindentation

2012 ◽  
Vol 1424 ◽  
Author(s):  
M. A. Mamun ◽  
A. H. Farha ◽  
Y. Ufuktepe ◽  
H. E. Elsayed-Ali ◽  
A. A. Elmustafa
Keyword(s):  
Thin Films ◽  
Pulsed Laser ◽  
Niobium Nitride ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Pile Up ◽  
Average Modulus

ABSTRACTNanomechanical and structural properties of pulsed laser deposited niobium nitride thin films were investigated using X-ray diffraction, atomic force microscopy, and nanoindentation. NbN film reveals cubic δ-NbN structure with the corresponding diffraction peaks from the (111), (200), and (220) planes. The NbN thin films depict highly granular structure, with a wide range of grain sizes that range from 15-40 nm with an average surface roughness of 6 nm. The average modulus of the film is 420±60 GPa, whereas for the substrate the average modulus is 180 GPa, which is considered higher than the average modulus for Si reported in the literature due to pile-up. The hardness of the film increases from an average of 12 GPa for deep indents (Si substrate) measured using XP CSM and load control (LC) modes to an average of 25 GPa measured using the DCM II head in CSM and LC modules. The average hardness of the Si substrate is 12 GPa.

Creep, Hysteresis, and Vibration Compensation for Piezoactuators: Atomic Force Microscopy Application

1999 ◽  
Vol 123 (1) ◽  
pp. 35-43 ◽  
Author(s):  
D. Croft ◽  
G. Shed ◽  
S. Devasia
Keyword(s):  
High Precision ◽  
Scanning Probe Microscopy ◽  
High Speed ◽  
Scanning Probe ◽  
Optical Systems ◽  
Positioning Precision ◽  
Force Microscopy ◽  
Atomic Force ◽  
Vibration Compensation ◽  
Adverse Affects

This article studies ultra-high-precision positioning with piezoactuators and illustrates the results with an example Scanning Probe Microscopy (SPM) application. Loss of positioning precision in piezoactuators occurs (1) due to hysteresis during long range applications, (2) due to creep effects when positioning is needed over extended periods of time, and (3) due to induced vibrations during high-speed positioning. This loss in precision restricts the use of piezoactuators in high-speed positioning applications like SPM-based nanofabrication, and ultra-high-precision optical systems. An integrated inversion-based approach is presented in this article to compensate for all three adverse affects—creep, hysteresis, and vibrations. The method is applied to an Atomic Force Microscope (AFM) and experimental results are presented that demonstrate substantial improvements in positioning precision and operating speed.

scholarly journals Characterisation of InGaN by Photoconductive Atomic Force Microscopy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1794 ◽  
Author(s):  
Thomas Weatherley ◽  
Fabien Massabuau ◽  
Menno Kappers ◽  
Rachel Oliver
Keyword(s):  
Atomic Force Microscopy ◽  
Cross Sections ◽  
Indium Content ◽  
Light Emitting ◽  
Force Microscopy ◽  
Turn On ◽  
Atomic Force ◽  
Voltage Curve ◽  
Current Voltage Curve ◽  
The Impact

Nanoscale structure has a large effect on the optoelectronic properties of InGaN, a material vital for energy saving technologies such as light emitting diodes. Photoconductive atomic force microscopy (PC-AFM) provides a new way to investigate this effect. In this study, PC-AFM was used to characterise four thick (∼130 nm) In x Ga 1 − x N films with x = 5%, 9%, 12%, and 15%. Lower photocurrent was observed on elevated ridges around defects (such as V-pits) in the films with x ≤ 12 %. Current-voltage curve analysis using the PC-AFM setup showed that this was due to a higher turn-on voltage on these ridges compared to surrounding material. To further understand this phenomenon, V-pit cross sections from the 9% and 15% films were characterised using transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. This identified a subsurface indium-deficient region surrounding the V-pit in the lower indium content film, which was not present in the 15% sample. Although this cannot directly explain the impact of ridges on turn-on voltage, it is likely to be related. Overall, the data presented here demonstrate the potential of PC-AFM in the field of III-nitride semiconductors.

REAL-TIME VISUALIZATION OF MORPHOLOGICAL EVOLUTION OF N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine THIN FILMS: VARIABLE TEMPERATURE ATOMIC FORCE MICROSCOPY STUDY

2002 ◽  
Vol 01 (05n06) ◽  
pp. 725-730 ◽  
Author(s):  
M. S. XU ◽  
J. B. XU ◽  
J. AN
Keyword(s):  
Thin Film ◽  
Atomic Force Microscopy ◽  
Morphological Evolution ◽  
Variable Temperature ◽  
Glassy State ◽  
Microscopy Study ◽  
Light Emitting ◽  
Force Microscopy ◽  
Atomic Force ◽  
Real Time Visualization

Variable temperature tapping mode atomic force microscopy is exploited to in situ visualize the morphological evolution of N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine (NPB) thin film. The apparent glass transition of the NPB thin film initially occurred at 60°C, proceeded until 95°C, and crystallization from the glassy state quickly appeared at 135°C. The NPB thin film gradually melted and disappeared when the temperature was above 175°C, revealing the underlying layer. These observations are technically helpful and significant to gauge the temperature dependent lifetime and luminance of organic light-emitting diodes.

SELF-ASSEMBLED Ge-DOTS FOR Si SOLAR CELLS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4347-4351 ◽  
Author(s):  
H. PRESTING ◽  
J. KONLE ◽  
H. KIBBEL
Keyword(s):  
Solar Cells ◽  
Open Circuit Voltage ◽  
Elevated Temperatures ◽  
Growth Conditions ◽  
Open Circuit ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
P Type

Silicon solar cells with embedded germanium (Ge) layers deposited as 3-dimensional islands in the Stranski-Krastanov growth mode have been grown by molecular beam epitaxy (MBE) to enhance the efficiency of Si thin film solar cells. The Ge-layers increase the infrared absorption in the base of the cell to achieve higher photocurrent which should overcome the loss in the open circuit voltage due to incorporation of a smaller bandgap material in the heterostructure. Up to 75 layers of Ge, each about 8 monolayers (ML) thick, separated by Si-spacer layers (9-18nm) have been deposited at rather elevated temperatures (700°C) on a standard 10Ωcm p-type Si-substrate. Island densities of 1011 cm -2 have been achieved by use of antimony (Sb) as surfactant. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to characterize the growth of Ge-islands under variuos growth conditions. Photocurrent measurements exhibit a higher photo-response in the infrared regime but a lower open circuit voltage of the fabricated solar cells compared to a Si-reference cell.

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