A Si p-π-n diode with β-FeSi 2 particles embedded in the unintentionally doped Si (p--type) was designed for determining the band offset at β-FeSi 2-Si heterojunction.When the diode is under forward bias,the elec...A Si p-π-n diode with β-FeSi 2 particles embedded in the unintentionally doped Si (p--type) was designed for determining the band offset at β-FeSi 2-Si heterojunction.When the diode is under forward bias,the electrons injected via the Si n-p- junction diffuse to and are confined in the β-FeSi 2 particles due to the band offset.The storage charge at the β-FeSi 2-Si heterojunction inversely hamper the further diffusion of electrons,giving rise to the localization of electrons in the p--Si near the Si junction,which prevents them from nonradiative recombination channels.This results in electroluminescence (EL) intensity from both Si and β-FeSi 2 quenching slowly up to room temperature.The temperature dependent ratio of EL intensity of β-FeSi 2 to Si indicates the loss of electron confinement following thermal excitation model.The conduction band offset between Si and β-FeSi 2 is determined to be about 0 2eV.展开更多
Extensive investigation of the passivating agents has been performed to suppress the perovskite defects.However,very few attentions have been paid to rationally design the passivating agents for the balance of the car...Extensive investigation of the passivating agents has been performed to suppress the perovskite defects.However,very few attentions have been paid to rationally design the passivating agents for the balance of the carrier confinement and transfer in quasi-2D perovskites,which is essential to achieve high-performance perovskite LEDs(PeLEDs).In this work,tributylphosphine oxide(TBPO)with moderate carbon chain length is demonstrated as a decent passivator for the quasi-2D perovskites by strengthening the carrier confinement for massive radiative recombination within the perovskites,and more importantly providing efficient carrier transfer in the quasi-2D perovskites.Benefiting from these interesting optoelectronic properties of TBPO-incorporated perovskites,we achieve high-efficient blue PeLEDs with an external quantum efficiency up to 11.5%and operational stability as long as 41.1 min without any shift of the electroluminescence spectra.Consequently,this work contributes an effective approach to promote the carrier confinement and transfer for high-performance and stable blue PeLEDs.展开更多
The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integra- tion of laser diodes on Si microprocessors. The major advantage of this newly proposed laser materi...The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integra- tion of laser diodes on Si microprocessors. The major advantage of this newly proposed laser material system is the small lattice mismatch between GaP and Si. However, the large threshold current density of these promising laser diodes on Si substrates shows that the carrier leakage plays an important role in Ga(NAsP)/GaP QW lasers. Therefore, it is necessary to investigate the band alignment in this laser material system. In this paper, we present a theoretical investigation to optimize the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs on GaP substrates. We examine the effect of nitrogen (N) concentration on the band offset ratios and band offset energies. We also provide a comparison of the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs with that of the GaNxAsyP1-x-y/Al2Ga1-2P QWs on GaP substrates. Our theoretical calculations indicate that the incorporations of N into the well and AI into the barrier improve the band alignment compared to that of the GaAsP/GaP QW laser heterostructures.展开更多
We studied the performance of AlGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) with an AlGaN buffer layer, which leads to a higher potential barrier at the backside of the two- dimension...We studied the performance of AlGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) with an AlGaN buffer layer, which leads to a higher potential barrier at the backside of the two- dimensional electron gas channel and better carrier confinement. This, remarkably, reduces the drain leakage current and improves the device breakdown voltage. The breakdown voltage of AlGaN/GaN double heterojunction HEMTs (-100 V) was significantly improved compared to that of conventional AlGaN/GaN HEMTs (-50 V) for the device with gate dimensions of 0.5 - 100μm and a gate-drain distance of 1μm. The DH-HEMTs also demonstrated a maximum output power of 7.78 W/mm, a maximum power-added efficiency of 62.3% and a linear gain of 23 dB at the drain supply voltage of 35 V at 4 GHz.展开更多
We study the growth of an InGaN and A1GaN/GaN/InGaN/GaN double heterojunction structure by metal organic chemical vapor deposition (MOCVD). It is found that the crystal quality of the InGaN back barrier layer signif...We study the growth of an InGaN and A1GaN/GaN/InGaN/GaN double heterojunction structure by metal organic chemical vapor deposition (MOCVD). It is found that the crystal quality of the InGaN back barrier layer significantly affects the electronic property of the A1GaN/GaN/InGaN/GaN double heterojunction. A high crystal quality InGaN layer is obtained by optimizing the growth pressure and temperature. Due to the InGaN layer polarization field opposite to that in the A1GaN layer, an additional potential barrier is formed between the GaN and the InGaN layer, which enhances carrier confinement of the 2DEG and reduces the buffer leakage current of devices. The double het- erojunetion high-electron-mobility transistors with an InGaN back barrier yield a drain induced barrier lowering of 1.5 mV/V and the off-sate source-drain leakage current is as low as 2.6μA/mm at VDS = 10 V.展开更多
文摘A Si p-π-n diode with β-FeSi 2 particles embedded in the unintentionally doped Si (p--type) was designed for determining the band offset at β-FeSi 2-Si heterojunction.When the diode is under forward bias,the electrons injected via the Si n-p- junction diffuse to and are confined in the β-FeSi 2 particles due to the band offset.The storage charge at the β-FeSi 2-Si heterojunction inversely hamper the further diffusion of electrons,giving rise to the localization of electrons in the p--Si near the Si junction,which prevents them from nonradiative recombination channels.This results in electroluminescence (EL) intensity from both Si and β-FeSi 2 quenching slowly up to room temperature.The temperature dependent ratio of EL intensity of β-FeSi 2 to Si indicates the loss of electron confinement following thermal excitation model.The conduction band offset between Si and β-FeSi 2 is determined to be about 0 2eV.
基金supported by National Key Research and Development Program(No.2017YFE0120400)Equipment fund,Platform Research Fund and feed fund(Grant Nos.2019157209 and 202011159254)+1 种基金University Grant Council of the University of Hong Kong,the General Research Fund(Grant Nos.17200518,17201819,and 17211220)Collaboration Research Fund(C7035-20G)from Hong Kong Special Administrative Region,China,as well as the National Natural Science Foundation of China(Nos.61875082 and 62105231)and the Natural Science Foundation of Jiangsu Province(No.BK20210712)。
文摘Extensive investigation of the passivating agents has been performed to suppress the perovskite defects.However,very few attentions have been paid to rationally design the passivating agents for the balance of the carrier confinement and transfer in quasi-2D perovskites,which is essential to achieve high-performance perovskite LEDs(PeLEDs).In this work,tributylphosphine oxide(TBPO)with moderate carbon chain length is demonstrated as a decent passivator for the quasi-2D perovskites by strengthening the carrier confinement for massive radiative recombination within the perovskites,and more importantly providing efficient carrier transfer in the quasi-2D perovskites.Benefiting from these interesting optoelectronic properties of TBPO-incorporated perovskites,we achieve high-efficient blue PeLEDs with an external quantum efficiency up to 11.5%and operational stability as long as 41.1 min without any shift of the electroluminescence spectra.Consequently,this work contributes an effective approach to promote the carrier confinement and transfer for high-performance and stable blue PeLEDs.
文摘The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integra- tion of laser diodes on Si microprocessors. The major advantage of this newly proposed laser material system is the small lattice mismatch between GaP and Si. However, the large threshold current density of these promising laser diodes on Si substrates shows that the carrier leakage plays an important role in Ga(NAsP)/GaP QW lasers. Therefore, it is necessary to investigate the band alignment in this laser material system. In this paper, we present a theoretical investigation to optimize the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs on GaP substrates. We examine the effect of nitrogen (N) concentration on the band offset ratios and band offset energies. We also provide a comparison of the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs with that of the GaNxAsyP1-x-y/Al2Ga1-2P QWs on GaP substrates. Our theoretical calculations indicate that the incorporations of N into the well and AI into the barrier improve the band alignment compared to that of the GaAsP/GaP QW laser heterostructures.
基金Project Supported by the National science and Technology Major Project of thc Ministry of Science and Technology of China(No. 2008ZX01002-002)the Major Program and the Key Program of the National Natural science Foundation of China(Nos.60890191, 60736033)
文摘We studied the performance of AlGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) with an AlGaN buffer layer, which leads to a higher potential barrier at the backside of the two- dimensional electron gas channel and better carrier confinement. This, remarkably, reduces the drain leakage current and improves the device breakdown voltage. The breakdown voltage of AlGaN/GaN double heterojunction HEMTs (-100 V) was significantly improved compared to that of conventional AlGaN/GaN HEMTs (-50 V) for the device with gate dimensions of 0.5 - 100μm and a gate-drain distance of 1μm. The DH-HEMTs also demonstrated a maximum output power of 7.78 W/mm, a maximum power-added efficiency of 62.3% and a linear gain of 23 dB at the drain supply voltage of 35 V at 4 GHz.
基金Project supported by the Major Program and Key Project of National Natural Science Foundation of China(Nos.60890191,60736033)the National Key S&T Special Project(No.2008ZX01002)
文摘We study the growth of an InGaN and A1GaN/GaN/InGaN/GaN double heterojunction structure by metal organic chemical vapor deposition (MOCVD). It is found that the crystal quality of the InGaN back barrier layer significantly affects the electronic property of the A1GaN/GaN/InGaN/GaN double heterojunction. A high crystal quality InGaN layer is obtained by optimizing the growth pressure and temperature. Due to the InGaN layer polarization field opposite to that in the A1GaN layer, an additional potential barrier is formed between the GaN and the InGaN layer, which enhances carrier confinement of the 2DEG and reduces the buffer leakage current of devices. The double het- erojunetion high-electron-mobility transistors with an InGaN back barrier yield a drain induced barrier lowering of 1.5 mV/V and the off-sate source-drain leakage current is as low as 2.6μA/mm at VDS = 10 V.