| With the rapid development of information technology,there is an urgent demand to seek new information memory devices and optoelectronic devices in the field of information storage and optoelectronic information processing.Memristor（memtransistor）and photodetector（phototransistor）with transistor structure have attracted more attentions because of their advantages,such as fast working speed,low power consumption,higher integration,good sensitivity,strong regulation ability and so on.Owing to its excellent electrical and optical properties,two-dimensional layered semiconductor materials can be used as resistive materials of memory transistors and photosensitive materials of phototransistors.To improve the performances of devices to a greater extent,on the one hand,it is necessary to explore two-dimensional semiconductor materials with higher mobility,good photosensitivity and stable performance.On the other hand,two-dimensional van der Waals heterostructures can be constructed through energy band matching to take full advantage of the unique characteristics of each material.In view of these,in this paper the stable Mo S2 layer was selected as the starting point,then multilayer Mo S2 and van der Waals heterojunction based on Mo S2 were selected as the channel materials of transistors,and the working performances and physical mechanisms of the two transistors under photoelectric regulations were studied.The main contents and achievements are listed as follows:（1）The Au/Cr/Mo S2/Cr/Au back-gate memtransistors with multilayer Mo S2resistive materials were fabricated on Si O2/p+Si substrate by micromechanical exfoliation method.The influences of electric field,optical field and the combination of electric field and the optical field on the resistance variations of the device are tested and analyzed.The results show that the multilayer Mo S2 memtransistors have good non-volatile bipolar resistive switching behaviors,and the switching ratio of the device can be regulated in a wide range（100～105）when Vg is adjusted in the range of（-7 V～+20 V）.Moreover,the Mo S2 memtransistors can realize the conversion of resistive switching between unipolar and bipolar by changing the incident wavelengths.Under the combination regulation of optical field and electric field,the device exhibits good switching characteristics and multi-port regulation capability.（2）On the basis of the above research,the Ga Se/Mo S2 heterojunction back-gate memtransistor was fabricated on Si O2/p+Si substrate by the alignment transfer method of mechanical stacking.It is shown that the device has excellent nonvolatile bipolar resistive switching behavior.When Vds is negative,the device can achieve a wide range of switching ratio（10～105and Vg in the range of-10 V～+15 V）;When Vds is positive,by changing the incident the wavelength of light,the switching ratio can also be regulated in a very large range（10～106）.Moreover,under the coordinated regulation of light field and electric field,the on-off ratio of the device is further improved to2.87×107(Vds is positive),and the on-off ratio is increased by 13%when Vds is negative（Vg=15 V）.Compared with the multilayer Mo S2 back-gate memtransistor,the Ga Se/Mo S2 heterojunction back-gate memtransistor exhibits more excellent resistive switching characteristics and multi-port control capability.（3）In addition,the Hf Se2/Mo S2 heterojunction phototransistor based on back gate structure is also prepared by mechanical stacking alignment transfer method.The optical responsivity of the device is up to 1.42×103 A/W,the specific detection rate reachs 1.39×1015 cm Hz1/2W-1.Under zero bias operation,the device has ultra-low dark current（1.22 f A）and optical response of 10.2 A/W.The device shows excellent photoelectric performance in the broadband range from NUV to NIR with or without external bias,and has effective gate tunability for light dark current（the light dark current switching ratio is about 105）.The Hf Se2/Mo S2 heterojunction phototransistor not only shows wide spectral response and high sensitivity,but also can realize self driven detection. |
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