Research On Graphene And Gallium Arsenide Heterojunction Optoelectronic Devices

The thickness of single atomic layer for graphene makes its intrinsic absorption of light is very low.It is so hard to obtain photoelectric devices with a high performance depending on graphene.Gallium arsenide is a?-?semiconductor material,with a sphalerite structure similar to diamond and a direct band gap of 1.42eV.The electron mobility in GaAs is very high,more than six times that of silicon.And saturated drift velocity of its electron is extremely high.Due to the difference of work function between graphene and GaAs,schottky junctions will be formed at the interface between them.Morever,the devices fabricated by using the schottky junction have a stronger optical absorption and photoelectric response.In this letter,we firstly designed and fabricated a schottky junction diodes.We studied the characteristics of dark current and photoelectric response of the diodes.It indicated that both of schottky junction barrier height and ideality factor were affected by temperature from the experimental results.And it can generate a stronger responsivity.Under zero bias voltage,the responsivity,detectivity and on-off ratio of this diodes can reach 4.59 mA/W,2.29×10¹00 cm Hz¹/2/2 W^-11 and 10³,respectively.Secondly,we designed and fabricated a near infrared detector based on graphene-GaAs schottky junction,and studied its photoelectric response.It showed a stronger photoelectric response in the visible and near infrared wavelength,and can be adjusted by gate voltage.Here,by introducing InAs QDs,we discussed the effect of Graphene/In As QDs/GaAs hybrid heterostructure for photoelectric response.Meanwhile,by combining Graphene with GaAs based HEMT,and the formation of 2D electron gas at the interface between Graphene and GaAs,we designed and fabricated a novel detector.It demonstrated that a stronger photoelectric response can be produced in both microwave and terahertz wavelength.This can be attributed to the photothermoelectriceffectofGraphene,asymmetryofGraphene/GaAs heterostructure and non-resonance response of the plasma wave HEMT.From the experimental results,under a bias voltage,it can produce a photocurrent of 6.16?A and 0.113?A in microwave and terahertz wavelength.The responsivity of this device can reach 2.3×10⁴V/W and 1.105×10³V/W,and the noise equivalent power is8.66×10^-11W Hz^-1/21/2 and 4×10^-12W Hz^-1/2,respectively.In this letter,we fabricated and discussed the Graphene/GaAs schottky diode,Graphene/In As QDs/GaAs hybrid heterostructure near infrared detector and Graphene/GaAs-based HEMT terahertz detector.From experimental results,it showed that Graphene/GaAs heterostructure all can produce a stronger broadband photoelectric response and abundant responsive mechanisms in visible,near infrared,microwave and terahertz wavelength.This fully demonstrated the huge potential advantages of photodetectors based on Graphene/GaAs heterostructure,and it provide a better platform for the next research and applications of ultra-broadband photodetectors based on heterostructure in the future.