A. Tajani

Numerical Parameterization of Chemical-Vapor-Deposited (CVD) Single-Crystal Diamond for Device Simulation and Analysis

High-quality electronic-grade intrinsic chemical- vapor-deposited (CVD) single-crystal diamond layers having exceptionally high carrier mobilities have been reported by Isberg et al. This makes the realization of novel electronic devices in diamond, particularly for high-voltage and high-temperature applications, a viable proposition. As such, material models which can capture the particular features of diamond as a semiconductor are required to analyze, optimize, and quantitatively design new devices. For example, the incomplete ionization of boron in diamond and the transition to metallic conduction in heavily boron-doped layers require accurate carrier freeze-out models to be included in the simulation of diamond devices. Models describing these phenomena are proposed in this paper and include numerical approximation of intrinsic diamond which is necessary to formulate doping- and temperature-dependent mobility models. They enable a concise numerical description of single-crystal diamond which agrees with data obtained from material characterization. The models are verified by application to new Schottky m-i-p+ diode structures in diamond. Simulated forward characteristics show excellent correlation with experimental measurements. In spite of the lack of impact ionization data for single-crystal diamond, approximation of avalanche coefficient parameters from other wide-bandgap semiconductors has also enabled the reverse blocking characteristics of diamond diodes to be simulated. Acceptable agreement with breakdown voltage from experimental devices made with presently available single-crystal CVD diamond is obtained.

Transient current electric field profiling of single crystal CVD diamond

The transient current technique ( TCT) has been adapted for profiling of the electric field distribution in intrinsic single crystal CVD diamond. It was found that successive hole transits do not a ...

Termination Structures for Diamond Schottky Barrier Diodes

A comprehensive study on the off-state performance of synthetic single crystal (SSC) diamond Schottky barrier diodes (SBDs) is the subject of this paper. Three termination structures suitable for unipolar diamond power devices are numerically investigated. Comparisons between the three terminations, based on blocking performance and area consumption are presented. Optimum design parameters derived from simulations are included for each structure. Experimental results of reverse-biased diamond SBDs for the first time with ramp angle termination are also presented

High-Field Electrical Transport in Single Crystal CVD Diamond Diodes

Diamond is a semiconductor with many superior material properties such as high breakdown field, high saturation velocity, high carrier mobilities and the highest thermal conductivity of all materials. These extreme properties, as compared to other (wide bandgap) semiconductors, make it desirable to develop single-crystalline epitaxial diamond films for electronic device and detector applications. Future diamond devices, such as power diodes, photoconductive switches and high-frequency field effect transistors, could in principle deliver outstanding performance due to diamonds excellent intrinsic properties. However, such electronic applications put severe demands on the crystalline quality of the material. Many fundamental electronic properties of diamond are still poorly understood, which severely holds back diamond-based electronic device and detector development. This problem is largely due to incomplete knowledge of the defects in the material and due to a lack of understanding of how these defects influence transport properties. Since diamond lacks a shallow dopant that is fully thermally activated at room temperature, the conventional silicon semiconductor technology cannot be transferred to diamond devices; instead, new concepts have to be developed. Some of the more promising device concepts contain thin delta-doped layers with a very high dopant concentration, which are fully activated in conjunction with undoped (intrinsic) layers where charges are transported. Thus, it is crucial to better understand transport in high-quality undoped layers with high carrier mobilities. The focus of this doctoral thesis is therefore the study of charge transport and related electronic properties of single-crystalline plasma-deposited (SC-CVD) diamond samples, in order to improve knowledge on charge creation and transport mechanisms. Fundamental characteristics such as drift mobilities, compensation ratios and average pair-creation energy were measured. Comparing them with theoretical predictions from simulations allows for verification of these models and improvement of the diamond deposition process.

Numerical and Experimental Analysis of Single Crystal Diamond Schottky Barrier Diodes

We present our findings on the numerical and experimental analysis of diamond Schottky Barrier diodes (SBDs) comprising of intrinsic single crystal (SC) chemical vapour deposited (CVD) diamond layers grown on highly boron doped substrates also grown by CVD. Good correlation with experimental results has been achieved through numerical modelling that has incorporated previously reported data on transport physics and carrier activation. With our numerical model, we are able to match to within 12 to 15% of the measured forward characteristics of fabricated diamond SBDs up to 2 V in excess of the turn on voltage, for two different Schottky metals.

Highly efficient edge terminations for diamond schottky diodes

Two termination structures suitable for diamond Schottky diodes are presented in this paper. A thorough comparison between the two structures, concerning both electrical and geometrical aspects, is included. The study is based on theoretical models and extensive numerical results. High termination efficiencies, up to 93%, are reported

High voltage Schottky barrier diodes in synthetic single crystal diamond

Recent results proved the possibility of obtaining synthetic single crystal diamond with good crystal quality and excellent consistency. High voltage p-type Schottky barrier diodes (SBDs) have been fabricated on diamond, using gold (Au) as the Schottky metal and boron as doping material. In this study, on-state and off-state experimental and simulated data are presented and excellent theory-experiment agreement is revealed. The usage of diamond SBDs as ultra violet (UV) photodetectors is also analysed. On-state and off-state simulations, for different optical beam power densities, have been carried out and the theoretical data are provided.