A study has just been carried out on hot electron effects in GaAs/Al0.3Ga0.7As potential well barrier(PWB)diodes using both Monte Carlo(MC)and drift-diffusion(DD)models of charge transport.We show the operation and be...A study has just been carried out on hot electron effects in GaAs/Al0.3Ga0.7As potential well barrier(PWB)diodes using both Monte Carlo(MC)and drift-diffusion(DD)models of charge transport.We show the operation and behaviour of the diode in terms of electric field,mean electron velocity and potential,mean energy of electrons andΓ-valley population.The MC model predicts lower currents flowing through the diode due to back scattering at anode(collector)and carrier heating at higher bias.At a bias of 1.0 V,the current density obtained from experimental result,MC and DD simulation models are 1.35,1.12 and1.77μA/μm^2 respectively.The reduction in current over conventional model,is compensated to a certain extent because less charge settles in the potential well and so the barrier is slightly reduced.The DD model results in higher currents under the same bias and conditions.However,at very low bias specifically,up to 0.3 V without any carrier heating effects,the DD and MC models look pretty similar as experimental results.The significant differences observed in the I-V characteristics of the DD and MC models at higher biases confirm the importance of energy transport when considering these devices.展开更多
This paper presents the temperature dependence measurements characterisation of several InAs/GaAs quantum dots （QDs） solar cell devices. The devices with cylindrical geometry were fabricated and characterised on-waf...This paper presents the temperature dependence measurements characterisation of several InAs/GaAs quantum dots （QDs） solar cell devices. The devices with cylindrical geometry were fabricated and characterised on-wafer under 20 suns in a temperature range from 300°K to 430°K. The temperature dependence parameters such as open circuit voltage, short circuit density current, fill factor and efficiency are studied in detail. The increase of temperature produces an enhancement of the short circuit current. However, the open circuit voltage is degraded because the temperature increases the recombination phenomena involved, as well as reducing the effective band gap of the semiconductor.展开更多
This paper discusses the design of a wideband low noise amplifier（LNA） in which specific architecture decisions were made in consideration of system-on-chip implementation for radio-astronomy applications.The LNA de...This paper discusses the design of a wideband low noise amplifier（LNA） in which specific architecture decisions were made in consideration of system-on-chip implementation for radio-astronomy applications.The LNA design is based on a novel ultra-low noise InGaAs/InAlAs/InP pHEMT.Linear and non-linear modelling of this pHEMT has been used to design an LNA operating from 2 to 4 GHz.A common-drain in cascade with a common source inductive degeneration,broadband LNA topology is proposed for wideband applications.The proposed configuration achieved a maximum gain of 27 dB and a noise figure of 0.3 dB with a good input and output return loss（S11〈—10 dB,S22〈—11 dB）.This LNA exhibits an input 1-dB compression point of-18 dBm,a third order input intercept point of 0 dBm and consumes 85 mW of power from a 1.8 V supply.展开更多
基金supported by the College of Physical Sciences, University of Aberdeen, UK
文摘A study has just been carried out on hot electron effects in GaAs/Al0.3Ga0.7As potential well barrier(PWB)diodes using both Monte Carlo(MC)and drift-diffusion(DD)models of charge transport.We show the operation and behaviour of the diode in terms of electric field,mean electron velocity and potential,mean energy of electrons andΓ-valley population.The MC model predicts lower currents flowing through the diode due to back scattering at anode(collector)and carrier heating at higher bias.At a bias of 1.0 V,the current density obtained from experimental result,MC and DD simulation models are 1.35,1.12 and1.77μA/μm^2 respectively.The reduction in current over conventional model,is compensated to a certain extent because less charge settles in the potential well and so the barrier is slightly reduced.The DD model results in higher currents under the same bias and conditions.However,at very low bias specifically,up to 0.3 V without any carrier heating effects,the DD and MC models look pretty similar as experimental results.The significant differences observed in the I-V characteristics of the DD and MC models at higher biases confirm the importance of energy transport when considering these devices.
文摘This paper presents the temperature dependence measurements characterisation of several InAs/GaAs quantum dots （QDs） solar cell devices. The devices with cylindrical geometry were fabricated and characterised on-wafer under 20 suns in a temperature range from 300°K to 430°K. The temperature dependence parameters such as open circuit voltage, short circuit density current, fill factor and efficiency are studied in detail. The increase of temperature produces an enhancement of the short circuit current. However, the open circuit voltage is degraded because the temperature increases the recombination phenomena involved, as well as reducing the effective band gap of the semiconductor.
文摘This paper discusses the design of a wideband low noise amplifier（LNA） in which specific architecture decisions were made in consideration of system-on-chip implementation for radio-astronomy applications.The LNA design is based on a novel ultra-low noise InGaAs/InAlAs/InP pHEMT.Linear and non-linear modelling of this pHEMT has been used to design an LNA operating from 2 to 4 GHz.A common-drain in cascade with a common source inductive degeneration,broadband LNA topology is proposed for wideband applications.The proposed configuration achieved a maximum gain of 27 dB and a noise figure of 0.3 dB with a good input and output return loss（S11〈—10 dB,S22〈—11 dB）.This LNA exhibits an input 1-dB compression point of-18 dBm,a third order input intercept point of 0 dBm and consumes 85 mW of power from a 1.8 V supply.
