arXiv subjects

Peter Ramvall

Publications and source records attributed to Peter Ramvall.

3 recordsLinked to original sources

arXiv2026

Growth and characterization of GaN/Ga2O3 Nanowire Heterostructures for Ultraviolet Optoelectronics

Ultraviolet-range GaN/b-Ga2O3 heterostructures were fabricated and investigated in both planar and nanowire geometries using pulsed laser deposition and reactive magnetron sputtering from a liquid gallium target for b-Ga2O3 deposition, while both GaN nanowire arrays and planar p-type Mg-doped GaN layers were grown by metal-organic chemical vapor deposition. Precise control of film uniformity and thickness was achieved as confirmed by structural and morphology studies using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy. Planar n-Ga2O3/p-GaN heterojunction diodes were electrically and photoelectronically characterized, exhibiting pronounced rectifying behavior, high forward current and a visible-blind ultraviolet photoresponse under zero external bias, demonstrating intrinsic self-powered operation. Furthermore, GaN/b-Ga2O3 core/shell nanowire heterostructures were developed and systematically studied with a focus on morphology control and process optimization. The influence of deposition parameters on shell thickness, uniformity, and tapering was investigated, enabling improved conformality of the b-Ga2O3 coating on the M-plane facets of GaN nanowires. The results highlight the viability of physical vapor deposition techniques for forming GaN/b-Ga2O3 heterostructures and establish a pathway toward nanowire-based ultraviolet optoelectronic devices.

cond-mat.mtrl-sci↗

arXiv2021

Vertical GaN Devices: Process and Reliability

This paper reviews recent progress and key challenges in process and reliability for high-performance vertical GaN transistors and diodes, focusing on the 200 mm CMOS-compatible technology. We particularly demonstrated the potential of using 200 mm diameter CTE matched substrates for vertical power transistors, and gate module optimizations for device robustness. An alternative technology path based on coalescence epitaxy of GaN-on-Silicon is also introduced, which could enable thick drift layers of very low dislocation density.

physics.app-ph↗

arXiv2017

An efficient tight-binding mode-space NEGF model enabling up to million atoms III-V nanowire MOSFETs and TFETs simulations

We report the capability to simulate in a quantum mechanical tight-binding (TB) atomistic fashion NW devices featuring several hundred to millions of atoms and diameter up to 18 nm. Such simulations go far beyond what is typically affordable with today's supercomputers using a traditional real space (RS) TB Hamiltonian technique. We have employed an innovative TB mode space (MS) technique instead and demonstrate large speedup (up to 10,000x) while keeping good accuracy (error smaller than 1 percent) compared to the RS NEGF method. Such technique and capability open new avenues to explore and understand the physics of nanoscale and mesoscopic devices dominated by quantum effects. In particular, our method addresses in an unprecedented way the technological relevant case of band-to-band tunneling (BTBT) in III-V nanowire MOSFETs and broken gap heterojunction tunnel-FETs (TFETs). We demonstrate an accurate match of simulated BTBT currents to experimental measurements in a [111] InAs NW having a 12 nm diameter and a 300 nm long channel. We apply the predictivity of our TB MS simulations and report an in-depth atomistic study of the scaling potential of III-V GAA nanowire heterojunction n and pTFETs quantifying the benefits of this technology for low-power, low-voltage CMOS application. At VDD = 0.3 V and IOFF = 50 pA/um, the on-current (Ion) and energy-delay product (ETP) gain over a Si NW GAA MOSFET are 58x and 56x respectively.

cond-mat.mes-hall↗