Intrinsic Layer Thickness Research Articles

Intrinsic Poly-Si layer thickness: Its role in pinhole contact formation and interface passivation in poly-silicon on oxide solar cells

Tunnel oxide passivating contact (TOPCon) solar cells are characterized by high surface passivation and electrical transport efficiency due to the chemical passivation and field effect of the tunnel oxide and doped poly-silicon layers, respectively. Nevertheless, the passivation quality, implied open-circuit voltage (iVoc), and device lifetime are adversely affected by high-temperature processing, leading to Auger recombination and pinhole defects in the tunnel oxide layer. This study aimed to explore the introduction of intrinsic poly-silicon as an interlayer to improve thermal stability and assesses its effect on the passivation of the tunnel oxide interface. Findings indicate that an intrinsic poly-silicon interlayer with a minimum thickness of 18 nm prevents passivation degradation at elevated temperatures. Additionally, the incorporation of this interlayer facilitates the tuning of the doping profile in crystalline silicon, resulting in a diminished pinhole density and an enhanced iVoc of 714.9 mV. These results advance our understanding of TOPCon solar cell performance and provide a foundation for their further optimization.

First-principles study on the electronic and optical properties of pn-type SnO/MoS[formula omitted] heterojunction tuned by various intrinsic vacancy defects and layer thicknesses

The impact of various intrinsic point defects and layer thicknesses on the electronic structure and optical properties of pn-type SnO/MoS2 heterojunctions has been investigated using first-principles calculations in this study. SnO/MoS2 heterojunctions are indirect bandgap semiconductors, with a narrower bandgap compared to monolayer SnO and MoS2, which decreases with increasing thickness of SnO or MoS2 layers. Intrinsic vacancy defects with different valence states were introduced using the transfer to the real state model method, which ensures that ionized electrons or holes are placed in the real band edge states. The primary intrinsic vacancy defects in the SnO/MoS2 heterojunction are Sn vacancies, and the valence states of the defects significantly influence the defect formation energy. Under different growth conditions, the dominant defects transition between VSn2−, VSn−, VO, and VS as the Fermi level varies. The intrinsic monolayer (1/1) SnO/MoS2 heterojunction exhibits weak n-type doping characteristics, while the introduction of VSn− defects leads to a shift towards p-type doping. As the number of SnO layers increases, VSn2− and VS defects introduce defect levels of different degrees in the bandgap, acting as electron–hole recombination centers and facilitating the transition between p-type doping and metallic conductivity characteristics. Increasing the number of MoS2 layers introduces localized defect energy levels in the bandgap, leading to p-doping or n-doping characteristics. The intrinsic SnO/MoS2 heterojunction primarily absorbs in the near-ultraviolet region, while also exhibiting a certain absorption capacity in the visible and deep ultraviolet regions. The presence of Sn and S defects can enhance the response to visible light absorption.

Optimization of the performance of micromorph tandem solar cell a-Si/uc-Si

We have performed a Computer modeling using AMPS 1D and AFORS-HET for optimizing tandem cells on p-i-n/p-i-n configuration. We investigated the influence of the substrate temperature for doped layer deposition technique in the top cell performances and the influence of the thickness of the bottom cell in the density of current that present a crucial parameter in the current matching between subcells. The simulation results demonstrate in one hand that a top cell a-Si with doped layers deposited by PECVD with 1000C substrate temperature provides a notable increase in the efficiency, and in the other hand a bottom cell with 900nm thick intrinsic layer exhibit more density of current. The performances of micromorph cell obtained from simulation give a good agreement with experimental results and confirm the importance of the combination as a double junction solar cell

Effect of intrinsic layer structure parameters on PIN homogeneous junction InGaN solar cells

This article examines the importance of indium gallium nitride (InGaN) homo junction solar cells in advancing high-efficiency or multi-junction solar batteries. The influence of indium composition and intrinsic layer with different thicknesses and carrier densities of PIN homo junction InGaN solar battery and its internal mechanism was studied. According to the research results, as the thickness gradually expands, the conversion efficiency of the battery increases first, and there is almost no change after the thickness reaches 0.3 μm; as the electron doping concentration of the intrinsic layer enhances, the conversion efficiency of the battery first rises to a certain extent and then begins to decline. Under the appropriate indium composition, the efficiency of the solar cell can be significantly increased to 24.6% by selecting the appropriate intrinsic layer thickness and doping concentration.

Model development of lattice-matched p-GaInP/i-GaAs/n-GaInP hetero-junction solar cell and its performance optimization

We report an analytical model for our proposed lattice-matched hetero-junction p-GaInP/i-GaAs/n-GaInP solar cell with the incorporation of AlInP cap layer and MgF2/TiO2 anti-reflection region supported by numerical data obtained using SENTAURUS TCAD. We investigate the impact of intrinsic layer thickness, cap layer thickness, compositional variation of gallium in GaInP alloy used in p- and n-regions of pin solar cell and also studied the effect of indium tin oxide (ITO) anode contact on photovoltaic performance of solar cell in terms of performance matrices i.e., open circuit voltage (Voc), short circuit current density (Jsc), fill-factor and power conversion efficiency (PCE). Also the performance of the proposed solar cell is optimized by judiciously choosing intrinsic layer thickness, and cap layer thickness. Our proposed device featuring 2.1-μm thick i-layer, 156-nm thick cap layer with Ga0.5In0·5P/GaAs active region yields a PCE of 19.89% which turns out to be 67% improvement as compared to the conventional solar cell enabling the proposed design attractive for photovoltaic applications.

Role of doping concentration, thickness of intrinsic layer and number of layers of graphene in Graphene-Silicon heterojunction solar cells

Graphene has unique characteristic of zero band-gap. Its electrical properties can be widely tuned by varying the number of layers or by doping as p or n type with different materials. Due to high optical transmittance and zero band-gap, graphene can be used as both, electron, and hole extraction layer. We have simulated n-graphene/Silicon hetero-structure Ag/ITO/n-Graphene/a-Si:H/c-Si(p)/Ag using AFORS (Automat FOR Simulation of HETero structures) software under AM1.5 illumination and power density of 100 mW/cm2. Here, the thickness of a-Si:H i-layer from 0 to 20 nm, the n-type doping concentration of Graphene from 1 × 1010cm−3 to 1 × 1020cm−3 to get the optimized results. Corresponding to that, we studied the band diagram and hence barrier height, Quantum efficiency etc. The best power conversion efficiency obtained is 18.59% where the Voc is 611.8 mV, Jsc is 37.04 mA/cm2 and FF is 82.03% corresponding to i-layer thickness 5 nm, single layer graphene and n-type doping concentration of 1 × 1020cm−3.

Improved radiation resistance of flexible GaInP/GaAs dual junction solar cell by optimizing GaAs subcell i-layer

The radiation effects of flexible GaInP/GaAs solar cells under 1 MeV electron irradiation have been studied. GaAs subcell intrinsic layer thickness showed remarkable effects on the solar cell radiation resistance. Based on the integrated current density of subcells, GaAs is determined as the current-limiting subcell before and after irradiation regardless to the i-layer thickness, while GaInP subcell exhibits superior radiation resistance. For 1.5 × 1015 e/cm2 irradiation fluence, the remaining factors of maximum output power are 71.94%, 82.53%, and 82.38%, for GaInP/GaAs solar cells with 0, 0.6 μm, 1.0 μm thick i-layer, respectively. EQE spectra of GaAs subcell degraded more in long-wavelength area, due to the higher defect concentration in the base layer. The flexible GaInP/GaAs dual junction solar cell with 0.6 μm thick i-layer sample exhibited an initial conversion efficiency of 23.79%, and the remaining factor is 82.51% after 1.5 × 1015 e/cm2 fluence electron irradiation.

Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry

In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on the fact that, except for the intrinsic uncertainties of the emission and straggling of alpha particles, their trajectories at different incident angles are distinct, with smaller ones corresponding to the incidence perpendicular to the detector surface. The result obtained (711 ± 23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the diode herein investigated is suitable for high resolution charged particle spectrometry.

Eco-friendly methyl-ammonium tin-based planar p–n homojunction Perovskite solar cells: Design and performance estimation

In this study, the design and performance estimation of tin (Sn)-based planar [Formula: see text]–[Formula: see text] homojunction perovskite solar cell (PSC) have been carried out. Here, the effect of maintaining the intrinsic active layer thickness and replacing the intrinsic active perovskite [Formula: see text]-layer of a standard [Formula: see text]-[Formula: see text]-[Formula: see text] structure of lead (Pb)-free PSCs with a [Formula: see text]–[Formula: see text] homojunction is fully investigated. When the active layer is divided into a [Formula: see text]–[Formula: see text] junction layer, it increases the photo-generated electrons and holes efficiency due to the built-in electric field of the junction. Furthermore, in order to get a better insight, the effects of various technological and device dimensional parameters on the performance of the reported PSC have been studied. It has been reported that the thickness of the p-side with methyl-ammonium tin triiodide (MASnI[Formula: see text] layer must be greater than the n-side of the MASnI3 layer. Meanwhile, its acceptors concentration should be slightly lower than the donors’ concentration on the n-side of MASnI3 layer to achieve maximum power conversion efficiency (PCE). Using the optimized parameters, our design demonstrates an open-circuit voltage ([Formula: see text] of 0.89 V, short-circuit current density ([Formula: see text] of 32.36 mA/cm2, fill factor (FF) of 74.40%, and PCE of 21.46%. This advocates the huge potential and great opportunities for deploying these Pb-free PSCs for eco-friendly photovoltaic applications.

Study the effect of temperature variation and intrinsic layer thickness on the linear response of a PIN photodetector: A finite element method approach

Perhaps mentioning the place of Silicon Valley semiconductor companies in business and technology is enough to remind the place of semiconductors in today's world. One of the applications of semiconductors is in manufacturing detection devices. This research aims to investigate the linearity of the response of a PIN photodetector to incident light. For this purpose, we will first simulate a PIN photodetector using COMSOL Multiphysics 6.0 software. Then we expose this photodetector to the light emitted from the scintillator and check the linearity of the response in the range of wavelengths irradiated to it. The research was done on photodetector PINs that are made of two semiconductor materials, GaAs and Si. The temperature and thickness of the intrinsic layer of a photodetector greatly affect its outputs, such as Current Terminal, Quantum Efficiency, and Responsivity. Therefore, the effect of these two parameters on the linearity of the output response of a photodetector has been investigated. To monitor the linearity of the photodetector output in each mode, a Linear Fitting has been applied to the output of the photodetectors using the Origin Pro software, and the linearity of the output data has been controlled from the R-Square and Adjusted R-Square of this fitting. The investigation illustrates that the response of GaAs is more linear than that of Si in similar cases. For example, the GaAs photodetector in the thickness of 8 μm and at the temperature of T = 70 °C has Adjusted R-Square = 0.9972. In contrast, the Si photodetector has Adjusted R-Square = 0.9178 under the same conditions.

Numerical Study on the Effect of ZrS2 on CZTSSe Photovoltaic Device Using SCAPS 1-D

CZTSSe based photovoltaic devices are gaining attention recently. They have many favorable properties like less costly and simple manufacturing processes, comparably nontoxic and easily available constituent components, and most importantly, excellent optoelectronic properties. Herein, we propose a CZTSSe based solar cell and aim to report for the first time a new material for the buffer layer: Zirconium Sulphide (ZrS2). The suggested device here is Al-doped ZnO(AZO)/ZrS2/CZTSSe/Mo. Here we use a numerical simulation package called Solar Cell Capacitance Simulator or SCAPS 1-D to analyze the output of the device with varying input parameters. To explore the impact of the ZrS2 layer on the functioning of the suggested device,its donor density was changed from 1012 cm−3 to 1016 cm−3. The simulations indicate that the donor density doesn’t particularly affect the output parameters of the device within the tested range. Besides the influence of the ZrS2 layer, a study was also carried out to find the role of operating temperature and the intrinsic layer on the proposed device. Most of the parameters declined rapidly with the increase in temperature while they remain constant with the change in ZnO thickness. Efficiency dropped to 9% at 500K from 23 % at 300K and the efficiency of the device remained 23% with the variation of intrinsic layer thickness. As per the simulation results, we can conclude that ZrS2 is an appropriate material as buffer layer for photovoltaic devices with a CZTSSe absorber layer.

Enhancement Photovoltaic Performance of p-i-n Amorphous Silicon Solar Cells with Intrinsic Layer

The numerical simulation of a p-i-n amorphous silicon solar cell has been analyzed using the SCAPS-1D software. The effect of the thicknesses of the layers and doping concentration under the standard AM1.5 operating conditions are investigated on the output parameters cell, such as the open-circuit voltage Voc, the short-circuit current density Jsc, the fill factor FF, and the efficiency of power conversion.η. The simulation results indicated that the performance of the studied solar cell is related to temperature, p and n layer doping, and intrinsic layer thickness. The simulations revealed that the cell's performance is affected by these physical and photoelectric parameters. As a result, the experimental data was used to validate the simulation results. The experimental data and the simulation predictions were found to be in good accord. On the other hand, the obtained optimal parameters for high performance offer an efficiency of 11.61% with layer thicknesses (nm) of p, i, and n regions are respectively 9,300,100, and concerning n and p layers doping (cm-3) are respectively 1020 cm-3 and 1018 cm-3.

Analytical model of the drain current in amorphous silicon junction field effect transistors

This paper presents an analytical model of a hydrogenated amorphous silicon (a-Si:H) junction field effect transistor (JFET) based on a p-type/intrinsic/n-type stacked structure. The p-doped layer is connected to the transistor gate electrode, while the n-layer acts as the device channel. The analysis shows the effect of the geometrical and physical parameters of the intrinsic and n-doped layers on the transistor characteristics. In particular, the intrinsic layer thickness plays a central role in determining the depletion region of the n-channel and, as a consequence, the device threshold voltage. The drain current behavior achieved with a modeled parametric analysis is in very good agreement with the experimental drain current measured on fabricated JFET, both in triode and pinch-off regions. This demonstrates the model feasibility as an effective tool to design thin film electronic circuit as a sensor signal amplifier based on a-Si:H p-i-n junction.

Design of Mid-Infrared Ge1–x Snx Homojunction p-i-n Photodiodes on Si Substrate

This work reports an optimal design and modeling of a high-performance normal-incidence GeSn homojunction p-i-n PDs on p-doped silicon (Si) substrate via Intrinsic-Si buffer. Specifically, we optimize the Sn concentration and the absorption layer thickness to simultaneously achieve high-speed, responsivity, detectivity, and low-noise in the mid-infrared (MIR) spectral range (2-<inline-formula> <tex-math notation="LaTeX">$5 ~\mu \text{m}$ </tex-math></inline-formula>). We also show that a reduced defect density due to the homojunction GeSn layer can lead to a suppressed dark current. The photoresponse of the designed device was studied for the range between 1500&#x2013;3000 nm, and the calculated responsivity is 3.26 A/W and 1.27 A/W at 2000 nm and 2500 nm, respectively for Sn &#x003D; 9&#x0025;. A specific detectivity, linear dynamic range (LDR), noise-equivalent power (NEP), and the signal-to-noise ratio (SNR) of <inline-formula> <tex-math notation="LaTeX">$2.5\times 10^{10}$ </tex-math></inline-formula> Jones, 105.5 dB, <inline-formula> <tex-math notation="LaTeX">$40.9\times 10^{-15}\text{W}$ </tex-math></inline-formula> Hz^&#x2212;0.5, and 100.9 dB, respectively, were achieved at 2500 nm for Sn &#x003D; 9&#x0025;. Furthermore, the impact of intrinsic layer thickness and incident optical power was also studied in detail. The calculated results show that larger absorption layer thickness enhances the photocurrent, detectivity, LDR and SNR, however, the speed of the device degrades significantly. The increased incident optical power results in an increase in SNR and LDR of the device due to an increased photocurrent. The 3dB bandwidth was also calculated for varying Sn concentration and intrinsic layer thickness. The calculated result shows a 3dB bandwidth of &#x003E; 26.2 GHz at &#x2212;3V. All the calculated results show that the proposed device has significant potential applications in the MIR range.

Analysis and Optimization of the Performance of Hydrogenated Amorphous Silicon Solar Cell

As the name implies, hydrogenated amorphous silicon (a-Si: H) is composed of silicon atoms which are in a disordered configuration away from all Bravais lattices. The hydrogenated amorphous silicon was manufactured in 1969 where there was a renewed interest in non-hydrogenated amorphous silicon. The use of hydrogenated amorphous silicon as the active material in solar cells inefficient but cheap, is currently much studied. We have presented in this work, the results of the numerical simulation of a-Si: H solar cell by the wxAMPS (Analysis of Microelectronic and Photonic Structures) software and the results were compared with those found experimentally, we find a good agreement. For the efficiency there was a difference of 0.17%. We also study the influence of the thickness of a-Si: H intrinsic layer on the photovoltaic parameters of the solar cell. This allows considering the use of amorphous thinner layers for photovoltaic applications. The efficiency has a maximum value of 7.117 %, corresponding to a intrinsic layer thickness of 560 nm. The using a-Si:H alloys provide a good solution to enhance a-Si:H solar cell performance. The use of a-SiC:H as a p-type window layer in amorphous silicon solar cells is one of its primary photovoltaic applications. The wide band gap of p-a-SiC:H alloy used as window layer for minimizing the optical loss. To improve the efficiency of a-Si:H solar cell, we have study by simulation the performance of the (p) a-SiC:H/(i) a-Si:H/ (n) a-Si:H heterojunction solar cell. The effects of a-SiC:H window layer on the photovoltaic performance have been investigated, where the best initial conversion efficiency of 10.59%.

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Numerical modelling is used to confirm experimental and theoretical work. The aim of this work is to present how to simulate ultrathin hydrogenated amorphous silicon- (a-Si:H-) based solar cells with a ITO BRL in their architectures. The results obtained in this study come from SCAPS-1D software. In the first step, the comparison between the J-V characteristics of simulation and experiment of the ultrathin a-Si:H-based solar cell is in agreement. Secondly, to explore the impact of certain properties of the solar cell, investigations focus on the study of the influence of the intrinsic layer and the buffer layer/absorber interface on the electrical parameters ( J SC , V OC , FF, and η ). The increase of the intrinsic layer thickness improves performance, while the bulk defect density of the intrinsic layer and the surface defect density of the buffer layer/ i -(a-Si:H) interface, respectively, in the ranges [109 cm-3, 1015 cm-3] and [1010 cm-2, 5 × 10 13 cm-2], do not affect the performance of the ultrathin a-Si:H-based solar cell. Analysis also shows that with approximately 1 μm thickness of the intrinsic layer, the optimum conversion efficiency is 12.71% ( J SC = 18.95 mA · c m − 2 , V OC = 0.973 V , and FF = 68.95 % ). This work presents a contribution to improving the performance of a-Si-based solar cells.

High sensitivity x-ray detectors based on 4H-SiC p-i-n structure with 80μm thick intrinsic layer

In this work, a large size x-ray detector with a 25 mm2 active area is demonstrated based on a thick 4H-SiC p-i-n structure. The detector exhibits obvious merits of high photon sensitivity over 4 × 104 μC Gy−1 cm−2, good photon-response linearity, and high-temperature operation compatibility. Meanwhile, due to the ultralow leakage current level achieved, single photon detection performance for x-ray photons is further realized with energy resolutions of 1.1 and 4.9 keV at 5.9 and 59.5 keV, respectively. This work thus suggests the significant potentials of wide-bandgap SiC semiconductor for photon-resolved x-ray detection in a harsh environment.

High-efficiency and high-speed germanium photodetector enabled by multiresonant photonic crystal

Abstract High-efficiency and high-speed photodetectors with broadband responses are playing pivotal roles for wavelength-division multiplexing optical communications. Germanium photodetectors on silicon platforms exhibit potential cost advantage due to the compatibility for monolithic integration with silicon-based electronic circuits for signal amplification and processing. In this article, we report a normal incidence, germanium photodetector enabled by guided-mode resonances in photonic crystal, which successfully resolved the compromise between quantum efficiency, wavelength coverage and bandwidth requirement, a drawback usually faced by conventional photodetectors operating at normal incidence. The resonant photonic crystal structure is designed to support multiple resonances in the target wavelength range. With an intrinsic absorption layer thickness of 350 nm, the device achieved a high external quantum efficiency of 50% at 1550 nm, along with an enhancement around 300% for the entire C-band. Using a mesa diameter of 14 μm, the fabricated device exhibited a 3-dB bandwidth of 33 GHz and obtained clear eye diagrams at bit rate up to 56 Gbps. This work provides a promising method to design high-efficiency, high-speed, normal incidence germanium photodetectors for optical interconnect systems.

Charge-Plasma-Based Doping-Less Vertical Thyristor for Highly Integrated Volatile Memory-Cell

Conventional dynamic random-access memory (DRAM) has been facing a severe challenge to scale down to 10 nm size. Since the cell capacitor should be able to store sufficient charges of 25~30 fF/cell, high aspect ratio of cell capacitor is inevitable, resulting in capacitors leaning into each other. To overcome this issue coming from capacitor, the two-terminal vertical thyristor-based capacitorless memory was proposed as a candidate to replace current DRAM, which consists of n++-emitter/p+-base/n+-base/p++-emitter vertical structure using conventional Si technology. The two-terminal vertical thyristor-based capacitorless memory cell having n++-emitter/p+-base/n+-base/p++-emitter structure utilizes latch-up and -down features showing bi-stable current-voltage (I-V) characteristics, so that data 0 (D0) and data 1 (D1) states can be distinguished. Nevertheless, in two-terminal vertical thyristor-based capacitorless memory, in-situ doped epitaxial growth process of silicon layers is essential. As is well known, the major disadvantage of epitaxial growth process is low throughput ratio. Besides, it is difficult to form step junctions since the dopants diffuse out from their original position during the serial epi-processes due to the high process temperature. Diffusion of dopants near the junctions is unavoidable in conventional doped thyristor memory cell fabricated with epitaxial growth, as shown in SIMS profile of Fig. 1(a). By applying the concept of charge plasma, the novel doping-less vertical thyristor as volatile memory is proposed, as shown in Fig. 1(b). In contrast with conventional doped thyristor memory cells, doping-less thyristor memory cells have step junction, as shown in carrier concentration profile of Fig. 1(c). Consequently, the vertical energy band diagram for doping-less thyristor memory cells differ from that of doped thyristor memory cells, as shown in Fig. 1(d). In addition, the conventional thyristor memory cells have been suffered from off-state leakage current because of the misfit dislocations at the highly doped junctions. On the other hand, the doping-less thyristor memory cells are misfit dislocation-free as their junctions are formed by the charge plasma, not the dopants. Moreover, the coulomb scattering can be dramatically reduced in doping-less thyristor memory cells owing to the absence of dopant and space charge, leading to the higher carrier mobility. As a result, the doping-less thyristor memory cells have lower off-state leakage current and higher on-state current, as shown in the I-V curves of Fig. 1(e) and (f). In this work, the effect of gap oxide thickness, which decides the intrinsic layer thickness, on latch-up voltage was investigated as well. In addition, the impact of p- and n-base metal work-function on the latch-up voltage of doping-less thyristor memory cell was investigated. Finally, the optimized metal work-function and gap oxide thickness for the memory cell were discussed. Acknowledgment* This research was supported by Brain Korea 21 PLUS Program in 2020, the MOTIE (Ministry of Trade, Industry & Energy 10069063) and KSRC (Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device. Figure 1

The metastable constituent effects on size-dependent deformation behavior of nanolaminated micropillars: Cu/FeCoCrNi vs Cu/CuZr

Metastable high entropy alloys (HEAs) and amorphous metallic glasses (MGs), with the chemical disordered character, are intensively studied due to their excellent performance. Here, we introduce Cu to separately constrain these two metastable materials and comparatively investigate their deformation behaviors and mechanical properties of Cu/HEA FeCoCrNi and Cu/MG CuZr nanolaminated micropillars in terms of intrinsic layer thickness h and extrinsic pillar diameter D. The metastable HEA layers, as the hard phase in Cu/HEA micropillars, are stable and dominate the deformation, while transformation (crystallization) occurs in MG which plays a minor role in deformation of Cu/MG micropillars. The h-controlled deformation mode transits from the D-independent homogenous-like deformation at large h to the D-dependent shear banding at small h in both Cu/HEA and Cu/MG micropillars. Although both Cu/HEA and Cu/MG micropillars exhibit a maximum strain hardening capability controlled by h, the former manifests much lower hardening capability compared with the latter. The intrinsic size h and extrinsic size D have a strong coupling effect on the strength of Cu/HEA and Cu/MG micropillars. The strength of strength of Cu/HEA micropillars exhibits the D-dependent transition from “smaller is stronger” to “smaller is weaker” with increasing h. By contrast, the strength of Cu/MG micropillars exhibits the transition from bulk-like D-independent behavior at large h to small volume D-dependent behavior (smaller is stronger) at small h.