Electron Blocking Research Articles

Status and Regulation of the Fintech Industry

Fintech is the cross product of the financial industry and the technology industry. With the development of society, financial digitization and technology finance have become the development trend. Electronic payment, p2p lending, Robo-Advisor and block chain technology four industries have formed a scale. The current fintech industry has become an important supplement to the economic system. However, due to the short development time, there are still challenges such as high risk points and difficult supervision. Based on the existing industrial scale and business capacity, the continuous integration of fintech industry and society has become a future trend. In the long run, fintech enterprises should give full play to their advantages in technology reserve, optimize and improve products, maintain industry self-discipline and reduce risks. The society and the government also need to keep objective and inclusive, increase talent reserve and industry support, maintain active supervision, promote the establishment of relevant laws and regulations, and maintain a good industry ecology.

Evaluation of intensity-modulated electron FLASH radiotherapy in a clinical setting using veterinary cases.

The increased normal tissue tolerance for FLASH radiotherapy (FLASH-RT), as compared to conventional radiotherapy, was first observed in ultra-high dose rate electron beams. Initial clinical trials in companion animals have revealed a high risk of developing osteoradionecrosis following high-dose single-fraction electron FLASH-RT, which may be related to inhomogeneities in the dose distribution. In the current study, we aim to evaluate the possibilities of intensity-modulated electron FLASH-RT in a clinical setting to ensure a homogeneous dose distribution in future veterinary and human clinical trials. Our beam model in the treatment planning system electronRT (.decimal, LLC, Sanford, FL, USA) was based on a 10-MeV electron beam from a clinical linear accelerator used to treat veterinary patients with FLASH-RT in a clinical setting. In electronRT, the beam can be intensity-modulated using tungsten island blocks in the electron block cutout, and range-modulated using a customized bolus with variable thickness. Modulations were first validated in a heterogeneous phantom by comparing measured and calculated dose distributions. To evaluate the impact of intensity modulation in superficial single-fraction FLASH-RT, a treatment planning study was conducted, including eight canine cancer patient cases with simulated tumors in the head-and-neck region. For each case, treatment plans with and without intensity modulation were created for a uniform bolus and a range-modulating bolus. Treatment plans were evaluated using a target dose homogeneity index (HI), a conformity index (CI), the near-maximum dose outside the target ( ), and the near-minimum dose to the target ( ). By adding intensity modulation to plans with a uniform bolus, the HI could be improved (p=0.017). The combination of a range-modulating bolus and intensity modulation provided a further significant improvement of the HI as compared to using intensity modulation in combination with a uniform bolus (p=0.036). The range-modulating bolus also improved the CI compared to using a uniform bolus, both with an open beam (p=0.046) and with intensity modulation (p=0.018), as well as increased the (p=0.036 with open beam and p=0.05 with intensity modulation) and reduced the median (not significant). By using intensity-modulated electron FLASH-RT in combination with range-modulating bolus, the target dose homogeneity and conformity in canine patients with simulated tumors in complex areas in the head-and-neck region could be improved. By utilizing this technique, we hope to decrease the dose outside the target volume and avoid hot spots in future clinical electron FLASH-RT studies, thereby reducing the risk of radiation-induced toxicity.

The role of indium composition in InxGa1−xN prestrained layer towards optical characteristics of EBL free GaN/InGaN nanowire LEDs for enhanced luminescence

AbstractIn this work, an electron blocking layer (EBL) free light emitting diode (LED) nanowire is proposed with alternate prestrained layers of InxGa1−xN/GaN, which are inserted between the GaN/InGaN multi‐quantum wells (MQWs) and n‐GaN layer. This study signifies the role of prestrained layers on the piezoelectric polarization of LED nanowires, for enhanced luminescence. When compared with the conventional one, the EBL free LED nanowire with prestrained layer shows an enhancement of ~2.897% efficiency, which occurs due to the reduction of polarization field in the active region. The LED with 15% indium in the prestrained layer obtains a maximum efficiency of 85.21% along with a minimum efficiency droop of 3.848% at 40 mA injected current. The proposed III‐nitride LED nanostructure allows for achieving superior optical power across the output spectral range.

(Dielectric Science &Technology Thomas D. Callinan Award) Semiconductor Nanostructures for Optoelectronics and Energy Applications

Semiconductors have played an important role in the development of information and communications technology, solar cells, solid state lighting. Nanowires are considered as building blocks for the next generation electronics and optoelectronics. In this talk, I will present the results on growth of nanowires, nanomembranes and microrings and their optical properties. Then I will discuss theoretical design and experimental results on optoelectronic devices. In particular I will discuss nanowire and micro-ring lasers and integration of nanowires and microrings. I will also present the results on polarization sensitive, broad bandwidth THz detectors operating at room temperature. Nanowire based energy devices such as solar cells and photoelectrochemical (PEC) water splitting will be discussed. I will discuss about Neuro-electrodes to study brain signaling to understand dementia. Future prospects of the semiconductor nanostructures will be discussed.

The mechanism of NaTi2(PO4)3 aqueous electrochemical degradation revisited

NASICON structure type materials are attracting increasing attention as electrode active materials for ion insertion batteries and deionization devices. NaTi2(PO4)3 due to its favorable potential is among the most suitable negative electrodes for various applications in aqueous electrolytes. However, various parasitic processes limit its Coulombic efficiency, self-discharge characteristics, and capacity retention. Understanding and mitigation of these processes are essential in order to fully utilize the potential of such and similar materials. In this study, the degradation mechanisms of NaTi2(PO4)3 in aqueous electrolytes is studied in great detail. The results indicate that, to a different extent, both hydrogen evolution and oxygen reduction reactions are taking place during NaTi2(PO4)3 electrochemical cycling and contribute to pH increase. The latter reaction due to the presence of Ti(III) species is found to be prevalent in aerated electrolytes. There is virtually no degradation and capacity loss observed at pH 7, but it becomes significant at pH 10 even in oxygen-free electrolytes. Contrary to previous studies, this work shows that capacity loss is actually slower at lower C-rates. The post mortem X-ray diffraction analysis shows that only a fraction of capacity loss could be directly attributed to NaTi2(PO4)3 decomposition and even less to its dissolution into electrolyte. Therefore, most of the observed capacity fade during cycling is related to contact loss in the electrode structure which most likely comes from the formation of electron blocking aqueous interphasial layer.

Improving the hole injection efficiency in AlGaN DUV LEDs by minimizing the band offset at the p-EBL/hole supplier interface

In AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs), the large valence band offset between the Al-rich electron blocking layer (EBL) and p-AlGaN hole supplier weakens the chance of holes being injected into the active region. Only holes with kinetic energy larger than the barrier height at the EBL/p-AlGaN interface are allowed to climb over the EBL before entering the active region, limiting the hole injection efficiency and thus reducing the external quantum efficiency (EQE). In this work, we incorporate a thin AlGaN insertion layer between EBL and the p-AlGaN hole supplier to enhance the hole injection efficiency of DUV LEDs via regulating the energy band at the p-EBL/p-AlGaN interface. By systematically investigating and analyzing the effects of aluminum components in the insertion layers on the hole injection and the electron confinement, we found that the insertion layer with an Al composition of 45% can effectively enhance the EQE of DUV LEDs by 40.5% and suppress efficiency droop by 65.5%. The design strategy provides an effective approach to boost the hole injection efficiency for AlGaN-based DUV LEDs.

Self assembled electron blocking and lithiophilic interface towards dendrite-free solid-state lithium battery

The poor interfacial contact is one of the biggest challenges that solid-state lithium batteries suffer from. Reducing the solid-state electrolyte surface energy by transforming the interface from lithiophobic to lithiophilic is effective to promote the interfacial contact, but electronic conductive interphases usually increase the risk of electron attack, thus leading to uncontrollable Li dendrite growth. Herein, we propose a self-assembled thermodynamic stable LiI interphase to simultaneously improve the interfacial contact between the garnet electrolyte Li7La3Zr2O12 (LLZO) and Li anode, and prohibit the electron attack. The direct contact between LLZO and Li and the high temperature Li melting process was ascribed to Zr4+ reduction, which facilitated Li dendrite formation and propagation. With the modification of the high lithiophilic I2 thin film, the area specific interfacial resistance of LLZO/Li was reduced from 1525 Ω/cm2 to 57 Ω/cm2. More importantly, LLZO was protected from being reduced due to the outstanding electronic insulativity of the LiI interphase, which leaded to a high critical current density of 1.2/7.0 mA/cm2 in the time/capacity-constant modes, respectively.

Simultaneously improved hole injection and current uniformity in 293 nm AlGaN-based deep ultraviolet light-emitting diodes

Insufficient hole injection and current nonuniformity caused by the nature of the p-AlGaN hole injection layer (HIL) are two issues impeding the advances in the optical and electrical properties of AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). To simultaneously improve the hole injection efficiency and current uniformity, an Al-linearly-decreasing AlGaN PN junction (ALD AlGaN PN junction) is proposed to replace the conventional p-AlGaN HIL with a constant Al component. The barrier height for holes at the interface between the p-type electron blocking layer (p-EBL) and HIL as well as the hole concentration and resistance in the p-AlGaN HIL can be modulated at the same time by the proposed ALD AlGaN PN junction. As a result, the hole injection efficiency is enhanced due to the reduced barrier height at the p-EBL/HIL interface and the polarization-induced three-dimensional hole gas (3DHG) induced in the proposed ALD AlGaN PN junction HIL. In addition, the lateral current uniformity is improved by the properly regulated resistance in the p-AlGaN HIL, which can be ascribed to the additional barrier for holes in the valence band because of the incorporated ALD AlGaN PN junction. The proposed DUV LED with ALD AlGaN PN junction exhibits enhanced EQE by a factor of 39.2% at 100 A/cm2 and simultaneously improved current uniformity in the active region. This designed ALD AlGaN PN junction structure provides a promising strategy for achieving high-performance DUV LEDs.

Optimization of AlGaN-based deep UV LED performance by p-AlInGaN/AlInGaN graded superlattice electron blocking layer.

In this paper, we significantly improved the internal quantum efficiency and output power of AlGaN-based deep UV (DUV) LEDs by replacing the conventional p-AlGaN electron blocking layer (EBL) with the p-AlInGaN/AlInGaN graded superlattice (SL) EBL. Simulation results show that the introduction of the p-AlInGaN graded SL EBL improved the carrier distribution while having the lower electric field, thus increasing the radiative recombination rate in multiple quantum wells (MQWs). The highest IQE obtained by p-AlInGaN/AlInGaN graded SL EBL is 96.6%, which is 44.9% higher than the conventional p-AlGaN EBL with no efficiency droop. At the same time, the output power is 4.6 times that of the conventional p-AlGaN EBL. It is believed that the proposed p-AlInGaN graded SL EBL will be helpful in the development of high-performance DUV LEDs.

Resonant Tunneling Effects on the Double‐Barrier Electron Blocking Layer of a Nitride Deep‐UV Light‐Emitting Diode

The multi‐quantum‐barrier electron blocking layer (EBL) is reported to significantly improve efficiency by nearly 3 times over a single barrier in deep‐UV AlGaN light‐emitting diodes to deal with electron leakage. The improvement is usually attributed to the enhanced effective barrier height, and this article aims to explore the benefits of the tunneling effect by calculating the tunneling currents of electrons and holes through an Al0.6Ga0.4N/AlyGa1−yN double‐barrier EBL under external bias from opposite directions. The results show that the tunneling current for holes Jh is several orders of magnitude higher than that of the electrons Je as the barriers are with Al mole fraction y greater than 0.75 and thickness larger than 2 nm, which promises effective hole injection by tunneling without much electron leakage. Tunneling mechanism works better in EBL with higher and thicker barriers because the tunneling coefficients of light hole drop much slower than electrons due to its small effective mass. A proper distance between the barriers is needed to avoid electron leakage while holes tunnel through the EBL. Built‐in electric fields tilt the band to enlarge the peak‐to‐valley ratio. This work indicates that the tunneling effect substantially facilitates a multibarrier EBL to enhance carrier‐injection efficiency.

Reducing Computational Complexity of Neural Networks in Optical Channel Equalization: From Concepts to Implementation

In this paper, a new methodology is proposed that allows for the low-complexity development of neural network (NN) based equalizers for the mitigation of impairments in high-speed coherent optical transmission systems. In this work, we provide a comprehensive description and comparison of various deep model compression approaches that have been applied to feed-forward and recurrent NN designs. Additionally, we evaluate the influence these strategies have on the performance of each NN equalizer. Quantization, weight clustering, pruning, and other cutting-edge strategies for model compression are taken into consideration. In this work, we propose and evaluate a Bayesian optimization-assisted compression, in which the hyperparameters of the compression are chosen to simultaneously reduce complexity and improve performance. Next, this paper presents four distinct metrics (RMpS, BoP, NABS, and NLGs) that are discussed here that can be used to evaluate the amount of computing complexity required by various compression algorithms. These measurements can serve as a benchmark for evaluating the relative effectiveness of various NN equalizers when compression approaches are used. In conclusion, the trade-off between the complexity of each compression approach and its performance is evaluated by utilizing both simulated and experimental data in order to complete the analysis. By utilizing optimal compression approaches, we show that it is possible to design an NN-based equalizer that is simpler to implement and has better performance than the conventional digital back-propagation (DBP) equalizer with only one step per span. This is accomplished by reducing the number of multipliers used in the NN equalizer after applying the weighted clustering and pruning algorithms. Furthermore, we demonstrate that an equalizer based on NN can also achieve superior performance while still maintaining the same degree of complexity as the full electronic chromatic dispersion compensation block. We conclude our analysis by highlighting open questions and existing challenges, as well as possible future research directions.

Flexible and Stretchable Organic Electrochemical Transistors for Physiological Sensing Devices.

Flexible and stretchable bioelectronics provides a biocompatible interface between electronics and biological systems and has received tremendous attention for in situ monitoring of various biological systems. Considerable progress in organic electronics has made organic semiconductors, as well as other organic electronic materials, ideal candidates for developing wearable, implantable, and biocompatible electronic circuits due to their potential mechanical compliance and biocompatibility. Organic electrochemical transistors (OECTs), as an emerging class of organic electronic building blocks, exhibit significant advantages in biological sensing due to the ionic nature at the basis of the switching behavior, low driving voltage (<1 V), and high transconductance (in millisiemens range). During the past few years, significant progress in constructing flexible/stretchable OECTs (FSOECTs) for both biochemical and bioelectrical sensors has been reported. In this regard, to summarize major research accomplishments in this emerging field, this review first discusses structure and critical features of FSOECTs, including working principles, materials, and architectural engineering. Next, a wide spectrum of relevant physiological sensing applications, where FSOECTs are the key components, are summarized. Last, major challenges and opportunities for further advancing FSOECT physiological sensors are discussed.

High-Efficiency InGaN Photo Cell Irradiated by 532 nm Laser with AlGaN Electron Blocking Layer

In this paper, a high-efficiency InGaN photo cell irradiated by 532 nm laser (at green wavelength) with AlGaN electron blocking layer (EBL) is proposed based on the blue-green light window effect of seawater. Firstly, the InGaN/GaN multiple quantum wells (MQWs) structured material intercalated with AlGaN EBL was designed and grown for InGaN photo cells. Then, by measuring the AFM, XRD and PL of the material, it is found that the insertion of AlGaN EBL can effectively reduce the defect density and improve the steepness of the interface in the active region. Further, based on the above material characteristics, the performance of the InGaN photo cells with AlGaN EBL is evaluated in Silvaco software under 532 nm laser irradiation. The results show that the introduction of AlGaN EBL in InGaN photo cell can not only decrease the non-radiative recombination rates, but also reduce the piezoelectric polarization effect, which contribute to the transport of effective photo-generated carriers and eventually improve the conversion efficiency by 13.325% compared to that with conventional structure. These findings provide critical new insights on high-efficiency GaN-based Photo Cell irradiated by 532 nm laser in the application of underwater communications.

Red Electroluminescence from Light Emitting Diodes Based on Eu-Doped ZnO Embedded in p-GaN/Al2O3/n-ZnO Heterostructures

Heterojunction p-GaN/n-ZnO light emitting diode (LED) structure using Eu-doped ZnO (ZnO:Eu) as an active component is demonstrated in order to realize low-cost and environmentally-friendly red LEDs with sharp linewidth and temperature stability against surrounding environment including operating temperature and injection current. Chemically stable Al2O3 is inserted as an electron blocking layer between p-GaN and ZnO:Eu/n-ZnO in order to facilitate the injection of carriers into the ZnO:Eu active layer. Al2O3 insertion with a moderate thickness (∼10 nm) facilitates the carrier recombination at the ZnO layer with comparatively low resistivity. Device characteristics of the p-GaN/Al2O3/ZnO:Eu/n-ZnO LED structures show red luminescence under current injection with reversed bias voltage originated from Eu3+ ions in the ZnO host. Detailed optical characteristics of the ZnO:Eu layer in the LED structures utilizing the combined excitation emission spectroscopy measurement enable the identification of the luminescence centers contributing to Eu luminescence under both indirect excitation and collisional excitation. The luminescence center contributing to Eu luminescence under indirect excitation via the ZnO host is different from that under collisional excitation, which would pave the way to understand the Eu luminescence mechanism in ZnO:Eu, and hence realize high-brightness LED structures based on rare-Earth doped ZnO as an active component.

Thin Quaternary Layer and Staggered Electron Blocking Layers for Improved Ultraviolet Light-Emitting Diodes

We have carried out numerical investigations of AlGaN-based ultraviolet light-emitting diodes (UV LEDs). We have shown that the unequal carrier distribution, which is typical in III-N LEDs, is mitigated in the active region. To improve the performance, we have used a thin AlInGaN quaternary layer (QL) between the final quantum barrier (FQB) and the electron blocking layer (EBL). We have also compared the results with a staggered or step-graded electron blocking layer which is known to show enhanced device output. The hole insertion has been found to greatly improve in all the multiquantum wells (MQWs) of our numerically designed LEDs. The radiative recombination rate has been found to be enhanced by ∼82% in comparison to reference LED.

EXPERIMENTAL RESEARCH CHARACTERISTICS OF TRANSFORMATION BY THE OPTIC-ELECTRONIC MODULE OF THE AUTOMATIC CONTROL SYSTEM

Simulators of environmental state sensors are used to set up and control the efficiency of automatic process control systems. In some cases, it is convenient to use a voltage-resistance converter with an optoelectronic output module based on a controlled photoresistor as a simulator of potentiometric sensors.&#x0D; An optical-electronic voltage-to-resistance converter, which has a galvanic isolation of the output and has a linear characteristic in a given range of output resistance is developed. The developed converter allows to set the angular and free coefficients of the linear equation arbitrarily that describes the response function of the converter and correctly simulate the operation of a potentiometric state sensor of the controlled parameter. An operating model of the converter was developed and manufactured, experimentally determination of its response function for different values of the free coefficient, supply voltage and different options for the circuit design of the optoelectronic module was carried out.&#x0D; The principle of operation of the converter is based on a change in the resistance of photoresistors under the influence of optical radiation coming from a controlled source. The model of the converter consists of optical and electronic blocks. The optical block consists of an optical radiation source and two photoresistors simultaneously directed at it. The signal from one photoresistor is the output, and the signal from the second photoresistor is analyzed by the control circuit, which synchronously changes the illumination on the light-sensitive areas of the photoresistors through the brightness controller in accordance with the voltage level of the control and corrective signals.&#x0D; The experimentally determined response function of the converter in the initial section has a non-linearity in the zone of low input voltages, which is determined, foremost, by the limitation of the lamp brightness and depends on the scheme of its inclusion. The non-linearity zone in the researched converter can be significantly reduced by increasing the supply voltage. Within the given range of change of the output resistance of the rectilinear section of the response function, the output resistance of the converter is linearly related to the input voltage, according to the results of experimental measurements in natural laboratory conditions, the conversion error hasn’t exceeded 0.3%.

Solution-processed vanadium oxide by low-temperature annealing for silicon solar cells with hole selective contact

Transition metal oxides (TMOs) with high work function (V2O5, MoO3, WO3) are very promising hole selective materials for high-efficiency crystalline silicon solar cells, as they can provide excellent hole transport and electron blocking capabilities simultaneously. However, the TMOs are typically obtained using vacuum deposition techniques (thermal evaporation, atomic layer deposition or sputtering), for which the preparation process is complex and the requirement for the equipments is relatively high. In this work, we prepared vanadium oxide (V2O5-X) films using low-cost solution method as the hole-selective transport layer for silicon heterojunction solar cells. The low temperature post-annealing treatment at 150 °C reduces the surface roughness of film and improves the passivation contact performance with p-Si. Furthermore, annealing in an oxygen-deficient atmosphere (N2/H2 = 95/5) improves the carrier transport due to increased oxygen vacancies and enhances the surface passivation ascribed to the additional role of hydrogen. Combined with the annealing treatments and optimized device processes, the V2O5-X/p-Si heterojunction solar cells have achieved a conversion efficiency of 17.23%, which is the highest reported so far based on solution-processed V2O5-X for crystalline silicon solar cells.

High‐Performance Silver‐Doped Porous CuBi2O4 Photocathode Integrated with NiO Hole‐Selective Layer for Improved Photoelectrochemical Water Splitting

AbstractCuBi2O4(CBO) has received considerable attention owing to its ideal optical bandgap and positive photocurrent onset potential. However, CBO photocathodes exhibit poor charge carrier separation and transfer across the conducting substrate interface. Herein, a systematic incorporation of Ag+‐cations into nanosized porous CBO network (ACBO) using a simple pulsed‐electrodeposition method. In ACBO photocathode, the Ag+‐ions replace the Bi3+‐ions, thereby building an increased hole concentration, which further signifies the photogenerated electron‐hole separation. Additionally, introducing a low‐cost NiO hole‐selective layer between ACBO and the conducting substrate enables a back‐interface‐aided hole‐extraction and electron blocking, resulting in an improved charge transfer across the back interface. Compared with an unmodified CBO, the NiO/ACBO photocathode exhibits a three‐fold enhanced photocurrent performance. This enhances the photocurrent originating from the incorporation of a substantial amount of Ag+‐ions into the CBO structure, leading to an increased acceptor density as well as the formation of an appropriate hole‐selective layer across the back‐contact. The absorption percentage, time‐resolved photoluminescence, and photoelectrochemical impedance spectroscopy measurements unveil the potential light harvesting, charge separation, and transfer characteristics of the NACBO photoelectrode, respectively. Through this systematic study, an efficient and simple strategy is determined for developing ternary metal oxide‐based photocathode/photoanode systems for sustainable energy applications.

Performance Improvement of AlGaN‐Based Deep‐Ultraviolet Light‐Emitting Diodes with Multigradient Electron Blocking Layer and Triangular Last Quantum Barrier

The performance improvements of AlGaN‐based deep ultraviolet light‐emitting diodes (DUV‐LEDs) with multigradient electron blocking layer (EBL) and triangular last quantum barrier (LQB) are investigated. The results show that the maximum internal quantum efficiency (IQE) is improved by 44.9% and light output power (LOP) is improved by 58.1% at 200 A cm−2, exhibiting a tremendous improvement compared to the conventional structure. These improvements are mainly attributed to the fact that both multigradient EBL and triangular LQB can generate negative polarization charges in the graded composition layer, which leads to a significant increase in hole concentration compared to the conventional EBL and LQB structures. Meanwhile, the multigradient EBL can transform the conventional triangular barrier into an arc‐shaped barrier, increasing the electron potential barrier height and decreasing the hole potential barrier height. This unique design suppresses electron leakage and enhances hole injection, leading to a significant enhancement of the IQE and alleviation of the efficiency droop.

Demonstrating the electron blocking effect of AlGaN/GaN superlattice cladding layers in GaN-based laser diodes

Electron leakage currents seriously limit the power conversion efficiencies (PCEs) of gallium nitride (GaN)-based laser diodes (LDs). To minimize the leakage currents, electron blocking layers are generally applied in the p-type region. However, few works have discussed the electron blocking effect of a p-cladding layer, which is found to be critical in suppressing the leakage currents of an LD. In this work, we compare the blocking performance of uniform AlGaN p-cladding layers and AlGaN/GaN superlattice (SL) p-cladding layers with the same average Al component respectively. Both light-emitting diodes (LEDs) and LDs with the same epitaxy structures are characterized by light–current (L–I) and current–voltage (I–V) measurements. The latest analytical model of leakage currents is applied to fit the L–I curves of LEDs, where smaller leakage coefficients are observed in the SL structures compared with the uniform-layer structures. Eighty LDs with varying ridge widths are studied by comparing the threshold current densities, slope efficiencies, and PCEs. The SL-based p-cladding layer shows statistically significant advantages over a uniform AlGaN layer. The blocking effects of both scattering- and bound-state electrons in SLs are investigated theoretically. Repetitive reflection and thermal relaxation are responsible for the blocking effect of scattering-state electrons. Simulation results indicate that the tunneling effect of bound-state electrons through a miniband mechanism is insignificant at a large injection level due to a negative differential conductivity by the Esaki–Tsu effect. We demonstrate a better electron blocking performance of p-cladding layers based on SLs than uniform AlGaN layers in GaN-based LDs.