[paper] Perovskite Photodiodes

Dong Li and Anlian Pan

Perovskite sensitized 2D photodiodes

Light Sci Appl 12, 139 (2023)

DOI: 10.1038/s41377-023-01187-2

Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, Hunan University, Changsha, China

Abstract: A new type of perovskite sensitized programmable WSe2 photodiode is constructed based on MAPbI3/WSe2 heterojunction, presenting flexible reconfigurable characteristics and prominent optoelectronic performances. The unique design of MAPbI3/WSe2 device provides a new idea to fabricate high-performance programmable photodiodes. In addition, the combination of atomic thin 2D materials and ionic solids enables effective coupling between electronic transport and ionic transport, which may open up a new pathway for unconventional computing, information storage systems, and programmable optoelectronic devices.

FIG: Schematic view of MAPbI3/WSe2 device structure and working mechanism 

of the programmable perovskite sensitized WSe2 photodiode

[thesis] SPICE modeling of light and radiation effects in ICs

A novel approach for SPICE modeling of light and radiation effects in ICs

Chiara ROSSI

Présentée le 29 janvier 2021

à la Faculté des sciences et techniques de l’ingénieur Groupe de scientifiques IEL

Programme doctoral en microsystèmes et microélectronique

pour l’obtention du grade de Docteur ès Sciences

DOI:10.5075/epfl-thesis-8422

Modeling the interaction of ionizing radiation, either light or ions, in integrated circuits is essential for the development and optimization of optoelectronic devices and of radiation-tolerant circuits. Whereas for optical sensors photogenerated carriers play an essential role, high energy ionizing particles can be a severe issue for circuits, as they create high density of excess carriers in ICs substrate, causing parasitic signals. In particular, recent advances in CMOS scaling have made circuits more sensitive to errors and dysfunctions caused by radiation-induced currents, even at the ground level. TCAD simulations of excess carriers generated by light or radiation are not dedicated to large scale circuit simulations since only few devices can be simulated at a time and computation times are too long. Conversely, SPICE simulations are faster, but their accuracy is strictly dependent on the correctness of the compact models used to describe the devices, especially when dealing with photocurrents and parasitic radiation-induced currents.

The objective of this thesis is to develop a novel modeling approach for SPICE compatible simulations of electron-hole pairs generated by light and by high energy particles. The approach proposed in this work is based on the Generalized Lumped Devices, previously developed to simulate parasitic signals in High Voltage MOSFET ICs. Here, the model is extended to include excess carriers generation. The developed approach allows physics-based simulations of semiconductor structures, hit by light or radiation, that can be run in standard circuit simulators without the need for any empirical parameter, only relying on the technological and geometrical parameters of the structure, and without any predefined compact model. The model is based on a coarse mesh of the device to obtain an equivalent network of Generalized Lumped Devices. The latter predicts generation of excess carriers and their propagation, recombination and collection at circuit nodes through the definition of equivalent voltages, proportional to the excess carrier concentrations, and equivalent currents, proportional to the excess carrier gradients. The model is validated with commercial TCAD numerical simulations for different scenarios. Regarding light effects, the proposed strategy is applied to simulate various optoelectronic devices. Complete DC I-V characteristics of a solar cell and transient response of a photodiode are studied. Next, phototransistors are considered. After, a full pixel of a 3T-APS CMOS image sensor is analyzed. The photosensing device, described with Generalized Devices, is co-simulated with the in-pixel circuit, described with compact models. The impact of semiconductor parameters on pixel output and on crosstalk between adjacent pixels is predicted. Finally, radiation-induced soft errors in ICs are examined. Alpha particles at different energies hitting the substrate are simulated. Parasitic currents collected at contacts are studied as a function of particles position and energy. Funneling effect, which is a phenomenon specific to high injection, is also included in the model.

This work shows that the Generalized Lumped Devices approach can be successfully used for SPICE simulations of optoelectronic devices and for prediction of radiationinduced parasitic currents in ICs substrate. This thesis is a first step towards a complete and flexible tool for excess carriers modeling in standard circuit simulators.

Fig: Layout, mesh (gray dashed lines) and equivalent network of Generalized Lumped Devices (Generalized Homojunctions, Resistors and Diodes). The structure is uniformly illuminated from the left side, justifying a 1D discretization scheme.

[paper] CV of Graphene–Silicon Heterojunction Photodiodes

Sarah Riazimehr,  Melkamu Belete,  Satender Kataria,  Olof Engström and Max Christian Lemme

Capacitance–Voltage (C –V) Characterization 

of Graphene–Silicon Heterojunction Photodiodes

Advanced Optical Materials 

First Published Open Access: 07 May 2020

DOI: 10.1002/adom.202000169

Abstract: Heterostructures of 2D and 3D materials form efficient devices for utilizing the properties of both classes of materials. Graphene/silicon (G/Si) Schottky diodes have been studied extensively with respect to their optoelectronic properties. Here, a method to analyze measured capacitance–voltage (C –V) data of G/Si Schottky diodes connected in parallel with G/silicon dioxide/Si (GIS) capacitors is introduced. The accurate extraction of the built‐in potential (Φbi) and the Schottky barrier height (SBH) from the measurement data independent of the Richardson constant is also demonstrated.

Figure 2

Fig.: a) Cross section of the test device showing both MIS and GIS regions. b) Small‐signal C –V characteristics of Dtest (line) compared to a theoretically calculated C –V curve (dashed ) at 10 kHz.

Acknowledgements: Financial support from the European Commission (Graphene Flagship, 785219, 881603) and the German Ministry of Education and Research, BMBF (GIMMIK, 03XP0210) is gratefully acknowledged.