@article {48206, title = {CdSe quantum dot-based nanocomposites for ultralow-power memristors}, journal = {ACS Applied Nano Materials}, volume = {5}, year = {2022}, month = {JUN}, pages = {8502-8510}, type = {Article}, abstract = {

The explosion in digital communication with the huge amount of data and the internet of things (IoT) led to the increasing demand for data storage technology with faster operation speed, high-density stacking, nonvolatility, and low power consumption for saving energy. Metal chalcogenide-based quantum dots (QDs) show excellent nonvolatile resistive memory behavior owing to their tunable electronic states and control in trap states by passivating the surface with different ligands. Here, we synthesized high-quality colloidal monodispersed CdSe QDs by the hot injection method. The CdSe QDs were blended with an organic polymer, poly(4-vinylpyridine) (PVP), to fabricate an Al\textbackslashCdSe-PVP\textbackslashAl device. Our device shows excellent bipolar nonvolatile resistive random access memory (RRAM) switching behavior with a high current ON/OFF ratio (I-ON/OFF) of 6.1 x 10(4), and it consumes ultralow power. The charge trapping and detrapping in the potential well formed by the CdSe QD and PVP combination result in resistive switching. This CdSe-PVP-based resistive random access memory (RRAM) device with a high I-ON/OFF, ultrafast switching speed, high endurance, low operating voltage, and long retention period can be used as a high-performance and ultralow-power memristive device.

}, keywords = {memory switching, memristor, metal chalcogenides, nonvolatile, quantum dots}, doi = {10.1021/acsanm.2c01894}, author = {Bera, Jayanta and Betal, Atanu and Sharma, Ashish and Shankar, Uday and Rath, Arup Kumar and Sahu, Satyajit} } @article {48166, title = {Colloidal MoS2 quantum dots for high-performance low power resistive memory devices with excellent temperature stability}, journal = {Applied Physics Letters}, volume = {120}, year = {2022}, month = {JUN}, pages = {253502}, type = {Article}, abstract = {

Conventional memory technologies are facing enormous problems with downscaling, and are hence unable to fulfill the requirement of big data storage generated by a huge explosion of digital information. A resistive random access memory device (RRAM) is one of the most emerging technologies for next-generation computing data storage owing to its high-density stacking, ultrafast switching speed, high non-volatility, multilevel data storage, low power consumption, and simple device structure. In this work, colloidal MoS2 quantum dots (QDs) embedded in an insulating matrix of poly-(4vinylpyridine) (PVP) were used as an active layer to fabricate a RRAM device. The MoS2 QDs-PVP based RRAM device reveals an excellent nonvolatile resistive switching (RS) behavior with a maximum current on-off ratio (I-ON/I-OFF) of 10(5). High endurance, long retention time, and successive {\textquoteleft}{\textquoteleft}write-read-erase-read{\textquoteright}{\textquoteright} cycles indicate high-performance RRAM characteristics. The ultimate power consumption by this RRAM device is considerably low for energy saving. In addition, the MoS2 QDs-PVP based device shows RS behavior even at 130 degrees C. High I-ON/I-OFF, low operating power, high endurance, long retention time, and excellent stability with temperatures reveal that the MoS2 QDs-PVP based device can be a promising candidate for high-performance low power RRAM devices that can be operated at relatively higher temperatures. Published under an exclusive license by AIP Publishing.

}, issn = {0003-6951}, doi = {10.1063/5.0094892}, author = {Bera, Jayanta and Betal, Atanu and Sharma, Ashish and Rath, Arup Kumar and Sahu, Satyajit} } @article {48115, title = {Composition and surface morphology invariant high on-off ratio from an organic memristor}, journal = {ACS Applied Electronic Materials}, volume = {4}, year = {2022}, month = {MAR }, pages = {1109-1116}, type = {Article}, abstract = {

Material composition plays a crucial role in the device performance; thus, nonvolatile memory devices from a small molecule named 5-mercapto-1-methyl tetrazole (MMT) in an insulating polymer matrix of poly(4-vinyl pyridine) (PVP) were fabricated. The composition of the active material in the device was varied to observe its influence on the device{\textquoteright}s electronic properties. The device with a more or less weight ratio of MMT has a much smoother surface morphology, whereas when the contributions of MMT and PVP were equal, the average surface roughness increased. However, the maximum on-off current ratio for all the devices is 10(5), suggesting that the MMT molecule does not show any change in its characteristic properties when surrounded by an insulating material. When the device was fabricated without the polymer matrix, the surface morphology of the device completely changed as it was filled with large holes. These holes provide short-circuited pathways for the current by forming the direct metal contact between the top and bottom electrodes. The carrier transport through these devices follows various conduction mechanisms. Some of the dominating conduction mechanisms are direct tunneling and trap-free and trap-assisted space-charge-limited conduction.

}, keywords = {Nonvolatile memory, Polymer, small molecule, space-charge, tunneling}, doi = {10.1021/acsaelm.1c01234}, author = {Betal, Atanu and Bera, Jayanta and Sharma, Ashish and Rath, Arup K. and Sahu, Satyajit} } @article {48321, title = {Charge trapped CdS quantum dot embedded polymer matrix for a high speed and low power memristor}, journal = {Physical Chemistry Chemical Physics}, volume = {25}, year = {2023}, month = {FEB }, pages = {3737-3744}, type = {Article}, abstract = {

The data storage requirement in the digital world is increasing day by day with the advancement of the internet of things. In this respect, nonvolatile resistive random-access memory is an option that provides high density and low power data storage capabilities. In this work, zero-dimensional colloidal CdS quantum dots and a polymer composite at an appropriate ratio were used to fabricate a memristive device. Comparison with a pristine CdS quantum dot-based device reveals that a surrounding matrix around the quantum dots is needed for observing memristive behavior. The quantum dots embedded in the polymer matrix device showed extremely stable electrical switching behavior that can be operated for more than 300 cycles and 60 000 seconds. Moreover, the device needs extremely low power to operate at a very high speed. The smooth surface morphology dictates a charge trapping mechanism for the switching phenomenon; however, an interplay between different charge transport mechanisms leads to the fast switching and high on-off ratio of the device.

}, issn = {1463-9076}, doi = {10.1039/d2cp05014e}, author = {Betal, Atanu and Bera, Jayanta and Sharma, Ashish and Rath, Arup K. K. and Sahu, Satyajit} }