The Schottky contact which is a crucial interface between semiconductors and metals is becoming increasingly significant in nano-semiconductor devices. A Schottky barrier, also known as the energy barrier, controls the depletion width and carrier transport across the metal–semiconductor interface.Controlling or adjusting Schottky barrier height(SBH) has always been a vital issue in the successful operation of any semiconductor device. This review provides a comprehensive overview of the static and dynamic adjustment methods of SBH, with a particular focus on the recent advancements in nanosemiconductor devices. These methods encompass the work function of the metals, interface gap states,surface modification, image-lowering effect, external electric field, light illumination, and piezotronic effect. We also discuss strategies to overcome the Fermi-level pinning effect caused by interface gap states, including van der Waals contact and 1D edge metal contact. Finally, this review concludes with future perspectives in this field.
This study uses atomic layer deposition(ALD)to grow Ga_(2)O_(3)films on SiO_(2)substrates and investigates the influence of film thickness and annealing temperature on film quality.Schottky diode devices are fabricated based on the grown Ga_(2)O_(3)films,and the effects of annealing temperature,electrode size,and electrode spacing on the electrical characteristics of the devices are studied.The results show that as the film thickness increases,the breakdown voltage of the fabricated devices also increases.A Schottky diode with a thickness of 240 nm can achieve a reverse breakdown voltage of 300 V.The film quality significantly improves as the annealing temperature of the film increases.At a voltage of 5 V,the current of the film annealed at 900℃is 64 times that of the film annealed at 700℃.The optimum annealing temperature for Ohmic contact electrodes is 450℃.At 550℃,the Ohmic contact metal tends to burn,and the performance of the device is reduced.Reducing the electrode spacing increases the forward current of the device but decreases the reverse breakdown voltage.Increasing the Schottky contact electrode size increases the forward current,but the change is not significant,and there is no significant change in the reverse breakdown voltage.The device also performs well at high temperatures,with a reverse breakdown voltage of 220 V at 125℃.
Internal photoemission is a prominent branch of the photoelectric effect and has emerged as a viable method for detecting photons with energies below the semiconductor bandgap.This breakthrough has played a significant role in accelerating the development of infrared imaging in one chip with state-of-the-art silicon techniques.However,the performance of these Schottky infrared detectors is currently hindered by the limit of internal photoemission;specifically,a low Schottky barrier height is inevitable for the detection of low-energy infrared photons.Herein,a distinct paradigm of Schottky infrared detectors is proposed to overcome the internal photoemission limit by introducing an optically tunable barrier.This device uses an infrared absorbing material-sensitized Schottky diode,assisted by the highly adjustable Fermi level of graphene,which subtly decouples the photon energy from the Schottky barrier height.Correspondingly,a broadband photoresponse spanning from ultraviolet to mid-wave infrared is achieved,with a high specific detectivity of 9.83×1010 cm Hz1/2 W−1 at 2,700 nm and an excellent specific detectivity of 7.2×109 cm Hz1/2 W−1 at room temperature under blackbody radiation.These results address a key challenge in internal photoemission and hold great promise for the development of the Schottky infrared detector with high sensitivity and room temperature operation.
In this work,a novel one-time-programmable memory unit based on a Schottky-type p-GaN diode is proposed.During the programming process,the junction switches from a high-resistance state to a low-resistance state through Schottky junction breakdown,and the state is permanently preserved.The memory unit features a current ratio of more than 10^(3),a read voltage window of 6 V,a programming time of less than 10^(−4)s,a stability of more than 108 read cycles,and a lifetime of far more than 10 years.Besides,the fabrication of the device is fully compatible with commercial Si-based GaN process platforms,which is of great significance for the realization of low-cost read-only memory in all-GaN integration.
Chao FengXinyue DaiQimeng JiangSen HuangJie FanXinhua WangXinyu Liu
Developing high-efficiency photocatalysts for tetracycline hydrochloride(TCH)degradation is of great sig-nificance to ecosystems and human beings.In this work,a two-step process of exfoliation and re-stacking was performed to prepare re-stacked HTiNbO_(5) nanosheets(R-HTNS)and then coupled with Ti_(3)C_(2) MXene to construct Ti_(3)C_(2) MXene/R-HTNS(MX/RTS)with a 2D/2D Schottky heterojunction.These 2D/2D het-erostructures between Ti_(3)C_(2) MXene and R-HTNS can produce an internal electric field and provide max-imum interface area for efficient charge transfer across the intimate interface.The photocatalytic perfor-mance of samples was evaluated by TCH degradation under simulated sunlight.The MX/RTS composites,with an optimal sample of 3-MX/RTS,show enhanced photocatalytic activity for TCH degradation com-pared with R-HTNS.The characterization results reveal that the introduction of Ti_(3)C_(2) MXene can signif-icantly increase specific surface area for providing more reactive sites and broaden the light absorption region.Besides,the incident light energy is absorbed by the Ti_(3)C_(2) MXene component in MX/RTS compos-ites to generate photothermal energy(heat),which facilitates the charge carrier separation and surface reaction kinetics.Thus,the enhanced TCH photodegradation activity for MX/RTS composites is due to the introduction of Ti_(3)C_(2) MXene,which possesses the synergistic effect of the increased specific surface area,improved light-harvesting capacity,2D/2D Schottky heterojunction,and photothermal energy effect.Additionally,the TCH photodegradation behavior is deliberated with a detailed discussion on various co-existing ions.During TCH photodegradation,the active radical species are determined for 3-MX/RTS.Ac-cording to the characterization results,the possible TCH photodegradation pathway and mechanism over 3-MX/RTS are explored.This work may offer a novel insight for constructing MXene-based heterostruc-tured photocatalysts with high efficiency.
Wen XiaoHuan YuChenghao XuZhongyi PuXiangyu ChengFang YuChao LiuQinfang ZhangZhigang Zou