Impact of the Deposition Temperature on the Structural and Electrical Properties of InN Films Grown on Self-Standing Diamond Substrates by Low-Temperature ECR-MOCVD

At a Glance

Metadata	Details
Publication Date	2020-12-04
Journal	Coatings
Authors	Shuaijie Wang, Fuwen Qin, Yizhen Bai, Dong Zhang, Jingdan Zhang
Institutions	Dalian University of Technology, Shenyang Institute of Engineering
Citations	6
Analysis	Full AI Review Included

Technical Documentation & Analysis: InN Film Growth on Self-Standing Diamond Substrates

Executive Summary

This research validates the critical role of high-quality, self-standing diamond substrates in advancing Indium Nitride (InN) based optoelectronic and high-power electronic devices.

Core Achievement: Successful growth of highly c-axis oriented InN thin films on self-standing Polycrystalline Diamond (PCD) using Low-Temperature Electron Cyclotron Resonance Plasma-Enhanced Metal Organic Chemical Vapor Deposition (ECR-PEMOCVD).
Material Advantage: The superior thermal conductivity of diamond substrates dramatically improves the power durability and high-frequency performance of the resulting InN devices.
Optimal Recipe: Optimal structural, morphological, and electrical properties were achieved at a precise deposition temperature of 400 °C.
Crystallinity & Orientation: Films grown at 400 °C exhibited high-resolution RHEED patterns of broken rings, confirming high crystallinity and strong (0002) c-axis preferential orientation.
Surface Quality: Atomic Force Microscopy (AFM) confirmed a minimum root mean square (RMS) surface roughness of 3.7 nm at 400 °C, meeting the flatness requirements for high-power infrared detectors.
Electrical Performance: Optimal electrical properties were measured at 400 °C, including a mobility of 48.5 cm2/(V·s) and the lowest carrier concentration (0.92 x 1020 cm-3).

Technical Specifications

The following hard data points were extracted from the analysis of InN films grown on self-standing diamond substrates.

Parameter	Value	Unit	Context
Substrate Material	Polycrystalline Diamond (PCD)	N/A	Self-standing, mechanically polished
Substrate Thickness	0.5 - 0.8	mm	Prepared by DC glow discharge PCVD
InN Film Thickness	Up to ~350	nm	Grown via ECR-PEMOCVD
Optimal Deposition Temp	400	°C	Yields highest crystallinity and best electrical properties
Minimum Surface Roughness (RMS)	3.7	nm	Measured at 400 °C (AFM analysis)
Optimal Grain Size	47	nm	Calculated via Scherrer’s formula at 400 °C
Optimal Mobility	48.5	cm<sup>2</sup>/(V·s)	Measured at 400 °C (Hall Effect)
Optimal Carrier Concentration	0.92 x 10<sup>20</sup>	cm<sup>-3</sup>	Measured at 400 °C (Hall Effect)
Optimal Stress (σ)	-1.96	GPa	Compression stress along c-axis at 400 °C
InN Band Gap	~0.7	eV	Narrow band gap, suitable for near-infrared applications
Diamond Thermal Expansion	3.7 x 10<sup>-6</sup>	/K	Compared to InN (4 x 10<sup>-6</sup>/K)

Key Methodologies

The InN thin films were prepared using a multi-step process focusing on substrate preparation and controlled ECR-PEMOCVD growth.

Substrate Preparation (PCD)

Initial Substrate: Thick PCD films (0.5-0.8 mm) were grown on Mo substrates via DC glow discharge PCVD.
Self-Standing Creation: Mo substrates were removed using laser stripping to create self-standing diamond films.
Surface Planarization: Diamond films were mechanically polished to achieve a smooth nucleation surface suitable for InN deposition.
Chemical Cleaning: Substrates were immersed in a 3:1 mixture of sulfuric acid and phosphoric acid for 24 hours at room temperature to remove metal carbide layers.
Ultrasonic Cleaning: Sequential cleaning using toluene, acetone, ethanol, and deionized water.
Plasma Rinse: Substrates were rinsed in the reaction chamber using H2 plasma (60 sccm flow, 650 W microwave power) for 0.5 hours at room temperature.

ECR-PEMOCVD Growth Parameters

Indium Source: Trimethyl Indium (TMIn), maintained at 20 ± 1 °C using a semiconductor cold trap.
Nitrogen Source: High-purity N2 (inert gas), ionized by Electron Cyclotron Resonance (ECR) plasma using H2 as a carrier gas.
Buffer Layer:
- Duration: 30 minutes.
- N2 Flow Rate: 60 sccm.
- TMIn Flow Rate: 0.3 sccm.
- Temperature: Room Temperature (RT).
Main Layer Growth:
- Duration: 180 minutes.
- Microwave Power: 650 W.
- N2 Flow Rate: 100 sccm.
- TMIn Flow Rate: 0.6 sccm.
- Temperature Range Studied: 200 °C to 600 °C (Optimal: 400 °C).

6CCVD Solutions & Capabilities

This research highlights the necessity of high-quality, polished Polycrystalline Diamond (PCD) for next-generation InN-based optoelectronics requiring superior thermal management. 6CCVD is uniquely positioned to supply the required diamond materials and customization services to replicate and scale this research.

Applicable Materials

To replicate or extend this research, high-quality, mechanically polished PCD is essential.

Material Recommendation: Optical Grade Polycrystalline Diamond (PCD).
- Rationale: PCD offers the high thermal conductivity (up to 2000 W/m·K) necessary to manage the heat generated by high-power InN devices (LEDs, high-frequency transistors) while providing the large area required for commercial scaling.

Customization Potential

The study required specific substrate dimensions, thickness, and surface preparation. 6CCVD’s in-house capabilities directly address these needs.

Research Requirement	6CCVD Solution & Capability	Technical Advantage
Substrate Dimensions	Custom Plates/Wafers up to 125 mm (PCD)	We supply large-area PCD wafers, facilitating the transition from R&D scale (1.2 cm x 1.2 cm samples used in the study) to commercial production.
Thickness Control	PCD Thickness Range (0.1 µm to 10 mm)	We provide self-standing PCD substrates in the required 0.5-0.8 mm range, or custom thicknesses up to 10 mm for maximum heat spreading.
Surface Flatness	Precision Polishing Services	Guaranteed surface roughness of Ra < 5 nm for inch-size PCD. This meets or exceeds the nanometer-level flatness (3.7 nm RMS achieved in the study) critical for minimizing interfacial defects and ensuring high-quality InN epitaxy.
Device Integration	Custom Metalization Services	We offer internal deposition of standard contact metals (Au, Pt, Pd, Ti, W, Cu), enabling rapid prototyping of Hall effect measurement contacts or full device stacks for InN infrared detectors.

Engineering Support

The successful growth of InN on diamond is highly sensitive to substrate preparation, temperature, and lattice mismatch (19.2%). 6CCVD’s technical team specializes in optimizing diamond material properties for demanding heteroepitaxial applications.

Consultation Focus: 6CCVD’s in-house PhD team can assist researchers and engineers with material selection, surface termination (e.g., hydrogen or oxygen termination), and polishing specifications to optimize the diamond/InN interface for similar Group III Nitride Optoelectronic projects.
Global Logistics: We offer reliable global shipping (DDU default, DDP available) to ensure your custom diamond substrates arrive safely and promptly, regardless of location.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The progress of InN semiconductors is still in its infancy compared to GaN-based devices and materials. Herein, InN thin films were grown on self-standing diamond substrates using low-temperature electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) with inert N2 used as a nitrogen source. The thermal conductivity of diamond substrates makes the as-grown InN films especially attractive for various optoelectronic applications. Structural and electrical properties which depend on deposition temperature were systematically investigated by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Hall effect measurement. The results indicated that the quality and properties of InN films were significantly influenced by the deposition temperature, and InN films with highly c-axis preferential orientation and surface morphology were obtained at optimized temperatures of 400 °C. Moreover, their electrical properties with deposition temperature were studied, and their tendency was correlated with the dependence on micro- structure and morphology.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings10121185

References

1998 - AIN heteroepitaxial and oriented films grown on (111), (110) and (100) natural diamond faces [Crossref]
2009 - Growth of GaN on nano-crystalline diamond substrates [Crossref]
2011 - Realising epitaxial growth of GaN on (001) diamond [Crossref]
2009 - GaN grown on (111) single crystal diamond substrate by molecular beam epitaxy [Crossref]
2020 - GaN-on-diamond technology platform: Bonding-free membrane manufacturing process [Crossref]
2020 - Integration of GaN and diamond using epitaxial lateral overgrowth [Crossref]
2020 - Theoretical prediction of electronic and optical properties of haft-hydrogenated InN monolayers [Crossref]
2019 - Tree-like structures of InN nanoparticles on agminated anodic aluminum oxide by plasma-assisted reactive evaporation [Crossref]
2019 - Tuning the electronic, photocatalytic and optical properties of hydrogenated InN monolayer by biaxial strain and electric field [Crossref]