arXiv subjects

Jianming Li

Publications and source records attributed to Jianming Li.

15 recordsLinked to original sources

arXiv2026

Physical mechanisms of ohmic contact and tunnel diode: A novel explanation in terms of impurity-photovoltaic-effect resulting from infrared self-emission at room-temperature

A mechanism of quantum-mechanical tunneling is based on electron-wavefunction and is used to explain ohmic contact as well as tunnel and Zener diodes. Tunneling is the important example of wave-particle duality. In this study, an attempt is made to explain these devices in particle description. As is well known, any object at room-temperature emits infrared (IR) photons due to blackbody radiation. The process of heavy doping can cause a lot of defects, e.g. vacancies and interstitials. The self-absorption of the IR emission could be achieved through sub-band-gap excitations due to defect-related levels in forbidden energy gap, creating carriers. In a heavily doped p-n junction diode, some of the IR-generated carriers diffuse into the junction which has a built-in field in a depletion layer. The built-in field then sweeps out the carriers, producing IR photocurrent. The IR photocurrent is regarded as the reverse current of the p-n junction according to the precedent where impurity-photovoltaic-effect is used to explain circuit devices (arXiv:2510.18226). Also, a reverse bias voltage increases depletion layer width, but carrier diffusion length out of the depletion layer remains unchanged, and more IR-generated carriers created in and near the depletion layer can contribute to the IR current. In addition, heavy doping results in not only a great many IR-generated carriers but also avalanche effect at low voltage. As a result, total reverse current dramatically increases with voltage, thus a Schottky diode can be altered to create an ohmic contact and a p-n diode can become a tunnel diode. Considering the wave-particle duality, the combination of quantum-mechanical and photovoltaic mechanisms is suggested to explain these devices. Each mechanism plays a big or small role in the explanation.

physics.app-ph↗

arXiv2025

The origins of the leakage currents of p-n junction and Schottky diodes in all kinds of materials: A novel explanation based on impurity-photovoltaic-effect due to the self-absorption of the room-temperature infrared emission from materials

A p-n junction is the basic building block for various semiconductor devices. A Schottky diode has characteristics that are essentially similar to those of the p-n junction diode. As is known, the leakage currents of p-n and Schottky junctions affect the overall performance of the devices and reduce the reliability of the devices. In order to achieve optimum device design, it is essential to fully understand the physical principle of the leakage currents. In traditional theory, defects provide a path for leakage current to travel. In this study, a novel theoretical model based on impurity-photovoltaic-effect is proposed to explain the leakage currents. It is well known that any object at a room-temperature emits infrared (IR) photons due to blackbody radiation. As is also well known, there is no absolutely pure material, and any material contains unavoidable defects associated with impurities. The self-absorption of the IR emission could be achieved through the sub-band-gap excitations due to defect-related intermediate levels in forbidden energy band-gap, creating carriers (electrons and holes). Some of the carriers diffuse into the built-in electric field of the junction. The built-in field then sweeps out electrons and holes in opposite directions, forming IR-generated photocurrent. Therefore, the leakage current is regarded as photocurrent. In addition to p-n junctions, some junctions exist in many semiconductor devices such as p-i-n diode and charge-coupled device (CCD), and these junctions also have built-in field due to contact potential difference. In fact, every semiconductor device contains at least one junction. The novel model is expected to explain the leakage for all kinds of junctions with semiconductor built-in fields.

physics.app-ph↗

arXiv2025

Subspecialty-Specific Foundation Model for Intelligent Gastrointestinal Pathology

Gastrointestinal (GI) diseases represent a clinically significant burden, necessitating precise diagnostic approaches to optimize patient outcomes. Conventional histopathological diagnosis suffers from limited reproducibility and diagnostic variability. To overcome these limitations, we develop Digepath, a specialized foundation model for GI pathology. Our framework introduces a dual-phase iterative optimization strategy combining pretraining with fine-screening, specifically designed to address the detection of sparsely distributed lesion areas in whole-slide images. Digepath is pretrained on over 353 million multi-scale images from 210,043 H&E-stained slides of GI diseases. It attains state-of-the-art performance on 33 out of 34 tasks related to GI pathology, including pathological diagnosis, protein expression status prediction, gene mutation prediction, and prognosis evaluation. We further translate the intelligent screening module for early GI cancer and achieve near-perfect 99.70% sensitivity across nine independent medical institutions. This work not only advances AI-driven precision pathology for GI diseases but also bridge critical gaps in histopathological practice.

eess.IV↗

arXiv2024

External quantum efficiency above 100% in photovoltaic cells due to the technique raising efficiencies for all kinds of solar cells

A V-shaped module (VSM) photovoltaic technique, which breaks traditional concepts, has been proven by European and American scientists to enable power-conversion-efficiency to increase by 50% for thin-film solar cells. Furthermore, the VSM technique raises power-conversion-efficiency for all kinds of solar cells (J. Environ. Sci. Eng. A 12, 214 (2023). https://doi.org/10.17265/2162-5298/2023.06.002). Mysterious dark energy is thought to result in the surprising VSM effect. The VSM approach opens up new avenues to study photovoltaic physics. In this study, the external quantum efficiency (EQE) of commercial polycrystalline silicon solar cells in the VSM was investigated, which exhibits a surprising phenomenon of EQE above 100%. In theory, non-infrared light incident into a solar cell can cause infrared emission. The VSM could trap the emitted infrared photons and lead to extra photoexcited carriers. The easy-to-reproduce VSM effect is thus explainable. The energy of emitted infrared photons is considered as the so-called dark energy. This study provides new clues and evidences to unravel the mystery of the surprising VSM effect. The VSM technique could also be used to develop photodetectors for infrared and ultraviolet light respectively.

physics.app-ph↗

arXiv2023

AdaSfM: From Coarse Global to Fine Incremental Adaptive Structure from Motion

Despite the impressive results achieved by many existing Structure from Motion (SfM) approaches, there is still a need to improve the robustness, accuracy, and efficiency on large-scale scenes with many outlier matches and sparse view graphs. In this paper, we propose AdaSfM: a coarse-to-fine adaptive SfM approach that is scalable to large-scale and challenging datasets. Our approach first does a coarse global SfM which improves the reliability of the view graph by leveraging measurements from low-cost sensors such as Inertial Measurement Units (IMUs) and wheel encoders. Subsequently, the view graph is divided into sub-scenes that are refined in parallel by a fine local incremental SfM regularised by the result from the coarse global SfM to improve the camera registration accuracy and alleviate scene drifts. Finally, our approach uses a threshold-adaptive strategy to align all local reconstructions to the coordinate frame of global SfM. Extensive experiments on large-scale benchmark datasets show that our approach achieves state-of-the-art accuracy and efficiency.

cs.CV↗

arXiv2020

A Semantics-Assisted Video Captioning Model Trained with Scheduled Sampling

Given the features of a video, recurrent neural networks can be used to automatically generate a caption for the video. Existing methods for video captioning have at least three limitations. First, semantic information has been widely applied to boost the performance of video captioning models, but existing networks often fail to provide meaningful semantic features. Second, the Teacher Forcing algorithm is often utilized to optimize video captioning models, but during training and inference, different strategies are applied to guide word generation, leading to poor performance. Third, current video captioning models are prone to generate relatively short captions that express video contents inappropriately. Toward resolving these three problems, we suggest three corresponding improvements. First of all, we propose a metric to compare the quality of semantic features, and utilize appropriate features as input for a semantic detection network (SDN) with adequate complexity in order to generate meaningful semantic features for videos. Then, we apply a scheduled sampling strategy that gradually transfers the training phase from a teacher-guided manner toward a more self-teaching manner. Finally, the ordinary logarithm probability loss function is leveraged by sentence length so that the inclination of generating short sentences is alleviated. Our model achieves better results than previous models on the YouTube2Text dataset and is competitive with the previous best model on the MSR-VTT dataset.

cs.CV↗

arXiv2016

The CDEX Dark Matter Program at the China Jinping Underground Laboratory

The China Jinping Underground Laboratory (CJPL) is a new facility for conducting low event-rate experiments. We present an overview of CJPL and the CDEX Dark Matter program based on germanium detectors with sub-keV sensitivities. The achieved results, status as well as the R&D and technology acquisition efforts towards a ton-scale experiment are reported.

physics.ins-det↗

arXiv1997

A New Approach of Fermion Field on Lattice

A new approach to formulate the fermion field on lattice is introduced by proposing a new Dirac operator on lattice.This approach can eliminate the Fermion doubling problem, preserve the chiral symmetry and get the same dispersion relation for both Fermion and Boson fields.Then the Weinberg-Salam model on lattice may be formulated in this approach.

hep-lat↗

arXiv1997

A New Formulation in Lattice Theory

In this paper we propose a new approach to formulate the field theory on a lattice. This approach can eliminate the Fermion doubling problem, preserve the chiral symmetry and get the same dispersion relation for both Fermion and Boson fields. This gives us the possibility to write down the chiral model (such as the Weinberg-Salam model) on a lattice.

hep-lat↗

arXiv1996

Reconstruction of SU(5) Grand Unified Model In Noncommutative Geometry Approach

Based on the generalized gauge theory on $M^4\times Z_2\times Z_3$, we reconstructed the realistic SU(5) Grand Unified model by a suitable assignment of fermion fields. The action of group elements $Z_2$ on fermion fields is the charge conjugation while the action of $Z_3$ elements represent generation translation. We find that to fit the spontaneous symmetry breaking and gauge hierarchy of SU(5) model a linear term of curvature has to be introduced. A new mass relation is obtained in our reconstructed model.

hep-th↗

arXiv1996

Wilson--Yukawa Chiral Model on Lattice and Non-commutative Geometry

Based upon the mathematical formulas of Lattice gauge theory and non-commutative geometry differential calculus, we developed an approach of generalized gauge theory on a product of the spacetime lattice and the two discrete points(or a $Z_2$ discrete group). We introduce a differentiation for non-nearest-neighbour points and find that this differentiation may lead to the introduction of Wilson term in the free fermion Lagrangian on lattice. The Wilson-Yukawa chiral model on lattice is constructed by the generalized gauge theory and a toy model and Smit-Swift model are studied.

hep-lat↗

arXiv1994

Matrix Realization of Gauge Theory on Discrete Group $Z_2$

We construct a $2\times 2$ matrix algebra as representation of functions on discrete group $Z_2$ and develop the gauge theory on discrete group proposed by Starz in the matrix algebra. Accordingly, we show that the non-commutative geometry model built by R.Conquereax, G.Esposito-Farese and G.Vaillant results from this approach directly. For the purpose of Physical model building, we introduce a free fermion Lagrangian on $M_4\times Z_2$ and study Yang-Mills like gauge theory.

hep-th↗

arXiv1994

The $σ$-Model and Non-commutative Geometry

In terms of non-commutative geometry, we show that the $σ$--model can be built up by the gauge theory on discrete group $Z_2$. We introduce a constraint in the gauge theory, which lead to the constraint imposed on linear $σ$ model to get nonlinear $σ$ model .

hep-th↗

arXiv1994

A $SU(2)$ Generalized Gauge Field Model With Higgs Mechanism

By means of the non-commutative differential geometry, we construct an $SU(2)$ generalized gauge field model. It is of $SU(2) \times π_4(SU(2))$ gauge invariance. We show that this model not only includes the Higgs field automatically on the equal footing with ordinary Yang-Mills gauge potentials but also is stable against quantum correlation.

hep-th↗

arXiv1994

Standard Model With Higgs As Gauge Field On Fourth Homotopy Group

Based upon a first principle, the generalized gauge principle, we construct a general model with $G_L\times G'_R \times Z_2$ gauge symmetry, where $Z_2=π_4(G_L)$ is the fourth homotopy group of the gauge group $G_L$, by means of the non-commutative differential geometry and reformulate the Weinberg-Salam model and the standard model with the Higgs field being a gauge field on the fourth homotopy group of their gauge groups. We show that in this approach not only the Higgs field is automatically introduced on the equal footing with ordinary Yang-Mills gauge potentials and there are no extra constraints among the parameters at the tree level but also it most importantly is stable against quantum correlation.

hep-th↗