Excitons and fundamental transport properties of diamond under photo‐injection (Phys. Status Solidi A 10∕2016)
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2016-10-01 |
| Journal | physica status solidi (a) |
| Authors | N. Naka, H. Morimoto, Ikuko Akimoto |
| Institutions | Wakayama University, Kyoto University |
| Citations | 2 |
| Analysis | Full AI Review Included |
Excitons and Fundamental Transport Properties of Diamond Under Photo-Injection
Section titled “Excitons and Fundamental Transport Properties of Diamond Under Photo-Injection”Analysis of Research Pertaining to Diamond Electronic Grade Materials (Based on PSS-A, 2016 Feature Article by Naka, Morimoto, and Akimoto)
Executive Summary
Section titled “Executive Summary”This research focuses on the fundamental electronic characteristics of diamond, specifically investigating the generation, lifetime, and transport dynamics of excitons and free carriers when subjected to photo-injection. This area of study is crucial for advancing diamond applications in high-energy radiation detection, high-power electronics, and UV light emitters.
- Core Objective: Direct measurement and analysis of exciton and fundamental carrier transport properties in diamond materials.
- Key Techniques Used: Photo-injection (likely UV/VUV) coupled with Microwave (MW) absorption spectroscopy under an applied Magnetic field (B).
- Observed Phenomena: Clear evidence of carrier diffusion and spatial spreading, allowing quantification of transport mobility and lifetime.
- Material Requirement: Requires the highest purity Electronic Grade Single Crystal Diamond (SCD) to minimize defect trapping and ensure long carrier lifetimes.
- Application Relevance: Findings directly contribute to optimizing diamond performance for UV detectors, particle detectors, and high-frequency power switching devices.
- 6CCVD Value Proposition: We provide the necessary ultra-high purity MPCVD SCD substrates with exceptional surface polish (Ra < 1 nm) required for such sensitive fundamental measurements.
Technical Specifications
Section titled “Technical Specifications”The following table summarizes the material requirements and key experimental parameters inferred from the published research topic and typical exciton dynamics studies.
| Parameter | Value (Inferred/Required) | Unit | Context |
|---|---|---|---|
| Material Type | Single Crystal Diamond (SCD) | N/A | Essential for maximizing charge carrier mobility. |
| Purity Grade | Electronic Grade (Type IIa) | N/A | Ultra-low Nitrogen content required (typically < 5 ppb). |
| Carrier Generation | Photo-injection (Bandgap Excitation) | N/A | Requires deep UV energy, approximately 5.5 eV or above. |
| Operating Temperature | Cryogenic Range | K | Necessary for stabilizing excitons and minimizing thermal scattering. |
| Measurement Method | MW Absorption | N/A | Detection of induced transient conductivity/carrier resonance. |
| Surface Finish (Required) | Ra < 1 | nm | Minimizes surface recombination velocity and scattering effects. |
| Substrate Thickness | 100 - 500 | µm | Standard range for high-sensitivity transmission/transport studies. |
Key Methodologies
Section titled “Key Methodologies”The study utilizes a combination of advanced spectroscopic and photo-excitation techniques to probe the intrinsic properties of the diamond lattice. Replicating or advancing this work requires stringent control over material quality and measurement conditions.
- Material Selection and Preparation: Utilization of high-purity, low-strain SCD substrates to ensure long free carrier and exciton lifetimes. Precise polishing (Ra < 1 nm) is critical.
- Photo-Injection: Generation of electron-hole pairs (and subsequent excitons) via pulsed high-energy photons (Deep UV or VUV) exceeding the 5.5 eV diamond bandgap.
- Application of External Fields: Applying a static Magnetic Field (B) and a probing Microwave (MW) field simultaneously to induce and monitor cyclotron resonance phenomena.
- Spectroscopic Analysis: Monitoring the transient decay and absorption spectra of the photo-generated carriers using MW detection techniques.
- Spatial Mapping: Observing the spatial diffusion/spreading of the carrier cloud over time, enabling calculation of transport parameters like mobility and diffusion length.
6CCVD Solutions & Capabilities (Driving Research Success)
Section titled “6CCVD Solutions & Capabilities (Driving Research Success)”6CCVD is uniquely positioned to supply the highly specialized diamond materials and processing required for sophisticated fundamental research on excitons and carrier transport properties.
Applicable Materials
Section titled “Applicable Materials”To replicate the high-fidelity measurements discussed in this feature article, researchers require the highest quality MPCVD diamond.
- Electronic Grade Single Crystal Diamond (SCD): Our standard Electronic Grade SCD features nitrogen concentrations in the low ppb range, ensuring minimal deep level trapping and maximized carrier mobility, essential for long-lived exciton studies.
- Optical Grade SCD: Available with exceptionally low defect densities and controlled thickness (0.1 µm to 500 µm) suitable for UV photo-injection transparency and minimizing scatter loss.
Customization Potential
Section titled “Customization Potential”Fundamental studies often require non-standard geometries or specialized surface treatments. 6CCVD provides comprehensive customization to meet precise experimental demands.
| Service Category | 6CCVD Capability | Application Relevance |
|---|---|---|
| Custom Dimensions | Plates up to 125mm (PCD), large SCD R&D wafers. | Accommodates large-area photo-injection or complex detector arrays. |
| Precision Thickness | SCD thickness control from 0.1 µm up to 500 µm. | Tuning thickness to optimize VUV absorption depth and minimize bulk effects. |
| Ultra-Low Roughness | Polishing to Ra < 1 nm (SCD) and Ra < 5 nm (PCD). | Critical for minimizing surface recombination velocity and ensuring stable carrier transport measurements. |
| Custom Metalization | Deposition of Au, Pt, Pd, Ti, W, Cu. | Essential for creating precise ohmic or Schottky contacts required for Hall effect or electrical transport measurements alongside photo-injection. |
Engineering Support
Section titled “Engineering Support”Understanding the relationship between diamond growth parameters and electronic transport properties is our core expertise.
- 6CCVD’s in-house PhD team provides expert consultation on material selection, doping control (BDD for specific conductivity control), and surface preparation techniques required for similar Diamond Charge Carrier Transport projects.
- We offer DDP shipping terms globally, streamlining logistics for international research collaborations and ensuring timely delivery of sensitive substrates.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond is one of the emergent high-mobility materials that are promising for the use in future power electronics and optoelectronics. Both free carriers and excitons, i.e., electron-hole pairs bound by the Coulomb force, play important roles in the mobility of diamond. However, the transport measurement for doped diamond has long been limited by carrier freezing at deep impurity levels below 80 K. Recently, challenges were made to utilize photoexcited carriers and excitons in undoped diamond. A series of investigations performed in a wide temperature range and various excitation schemes are reviewed in the Feature Article by N. Naka et al. (pp. 2551-2563). The lower panels of the cover image represent extremely high exciton diffusivity measured at 7 K by timeresolved photoluminescence imaging. The upper panel shows a cyclotron resonance spectrum, which provides effective mass values and mobility of free carriers originating from exciton binary collisions. The new pieces of knowledge on the interplay between excitons and free carriers will lay a foundation for the optimum design of diamond-based devices.