N-Face Semi-Bulk Absorber Boosts Conversion Efficiency of InGaN Solar Cell

International audienceThe purpose of this paper is to investigate the N-face InGaN semi-bulk as a solution to achieve a high-efficiency solar cell based on III-nitride materials, which could mitigate the issues of both InGaN crystalline quality and charge polarization. Simulation of both InGaN bulk and semi-bulk with both N and Ga faces, using an analytical model, shows that this approach leads to a significant increase of the power conversion efficiency. It is found that the conversion efficiency of the new solar cell structure with 25% indium content is about three times larger than the one based on the fully relaxed bulk InGaN absorber (no detrimental effect of the polarization effect) with the same indium concentration. This approach could thus be beneficial to the realization of efficient InGaN-based solar cells

Design and fabrication process flow for high-efficiency and flexible InGaN solar cells

International audienc

Design and fabrication process flow for high-efficiency and flexible InGaN solar cells

International audienc

Transfer of III-nitride epitaxial layers onto pre-patterned silicon substrates for the simple fabrication of free-standing MEMS

International audienceIn recent years, the remarkable properties and potential applications of III-nitride (III-N) semiconductors have sparked a significant interest in the field of microelectromechanical systems (MEMS). Traditionally, III-N MEMS are fabricated through a process involving the epitaxial growth of III-N epilayers on a silicon substrate followed by etching the handle wafer to generate free-standing structures. In this study, we explore the potential of a relatively simple approach based on the two-dimensional (2D) material-based liftoff and transfer to fabricate III-N mechanical resonators. The methodology involves van der Waals epitaxy of III-N layers on 2D hexagonal-boron nitride (h-BN), which leverages the weak van der Waals adhesion between h-BN layers to lift off and transfer these layers from their original growth substrate to an alternative host substrate. The employed method is demonstrated by fabricating 600 nm thick GaN/AlGaN and 2.5 μm thick h-BN micro-resonators onto pre-patterned cavities etched in silicon substrates. These devices are characterized using laser Doppler vibrometry, enabling the observation of well-defined modes of vibration and resonant frequencies. Furthermore, finite element method simulations are performed to gain insights into the experimental observations and the mechanical properties of the transferred layers. This approach could be extended to transfer high-quality III-N MEMS devices onto various host substrates, including flexible substrates, and could be used to assess the mechanical properties of emerging III-N semiconductor materials

Van der Waals epitaxy by MOCVD of III-Nitrides using two-dimensional hexagonal boron nitride : applications and persperctives

conférence invitéeInternational audienc

Side-by-side comparison of pre- and post-transferred LEDs grown on 2D hexagonal boron nitride onto arbitrary substrates

International audienceWe present a critical study of LEDs on h-BN compared to the conventional LEDs on sapphire from materials characterizations, device fabrication to the device performances measurements performed before and after liftoff and transfer with and without intermediary adhesion layer to arbitrary substrates

Wafer-scale van der Waals Epitaxy of III-Nitride Devices on h-BN-An Overview of 2D/3D Epitaxy, Device Fabrication, Mechanical Release-Transfer Methods and Device Performances

Conférence invitéeInternational audienc