Toward High‐Performance Diamond Electronics: Control and Annihilation of Dislocation Propagation by Metal‐Assisted Termination

Abstract

A major obstacle limiting diamond electronics is dislocations, which deteriorate device properties. As threading dislocations (TDs) are normally inherited from the substrate to the epitaxial layer, control and annihilation of their propagation are important. Herein, metal-assisted termination (MAT), in which the propagation of dislocations is suppressed by in situ metal doping, is proposed. Heavy W doping is realized by a hot-filament (HF) chemical vapor deposition (CVD) using heated wires at a high temperature of >2400-K. A large reduction of TD density is confirmed by cathodoluminescence studies and etch-pit analysis. The impact of dislocation reduction is investigated electrically. After insertion of the MAT buffer layer, Schottky barrier diodes (SBDs) show improved rectifying action and highly uniform characteristics even when substrates with high dislocation densities (mosaic and heteroepitaxial wafers) are used. The 3D structure of dislocation propagation is successfully captured by two-photon-excited photoluminescence (2PPL) imaging of Band-A luminescence. The 2PPL Band-A luminescence (without band-edge excitation) shows high spatial resolution in the depth direction. An abrupt decrease in TD density is captured for heteroepitaxial substrates with an inserted MAT buffer layer. The MAT technique provides an effective approach to realize high-performance diamond electronics.

Impact of Laser‐Induced Graphitization on Diamond Schottky Barrier Diodes

“…For the fabrication process of pVSBDs, a heavily boron‐doped (p + ) contact layer was homoepitaxially grown on the substrate using hot‐filament chemical vapor deposition (HFCVD). [ 23–25 ] The B concentration was 10 20 cm −3 . Next, a lightly boron‐doped (p − ) layer with a thickness of 2 μm was grown on the contact layer using microwave plasma‐enhanced CVD (PECVD).…”

“…For the fabrication process of pVSBDs, a heavily boron-doped (p þ ) contact layer was homoepitaxially grown on the substrate using hot-filament chemical vapor deposition (HFCVD). [23][24][25] The B concentration was 10 20 cm À3 . Next, a lightly boron-doped (p À ) layer with a thickness of 2 μm was DOI: 10.1002/pssa.202100846 Pseudovertical Schottky barrier diodes (SBDs) are fabricated on a single-crystal diamond substrate.…”

Chemical Vapor Deposition Single‐Crystal Diamond: A Review

“…[72] The further growth on the side plane confirmed a strong decrease by an order of magnitude in dislocation density. [26,72] The SC CVD diamond is used in X-ray beam position monitors, [73] X-ray monochromators, [74] and splitters, [75] detectors of charged high energy particles, [76,77] neutrons, [78][79][80] UV light, [81] and in dosimeters in radiotherapy, particularly for proton therapy [82] to combine good electronic properties and radiation [50] Copyright 2019, Wiley-VCH.…”

Dislocation density reduction using overgrowth on hole arrays made in heteroepitaxial diamond substrates

“…31 This technique was applied to heteroepitaxial diamond, leading to a reduction in dislocation density although no quantitative value was reported. 32 A high concentration of metallic impurity contamination still necessarily remains though, which is not always acceptable for electronic applications.…”