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An Er 2 O 3 capped SnO 2 nanostructure (NS) based memory device was synthesized on Si substrate by glancing angle deposition technique. Field emission scanning electron microscopy and transmission electron microscopy were used to verify the formation of the Er 2 O 3 capped SnO 2 NS. The Er 2 O 3 capped SnO 2 NSs were polycrystalline in nature as obtained from selected area electron diffraction analysis. Au metal contact was deposited over the Er 2 O 3 capped SnO 2 NS to fabricate a Au/Er 2 O 3 -SnO 2 /Si memory device. The Er 2 O 3 capped SnO 2 memory device showed a higher memory window of 1V, and higher charge storage capability (0.7 × 10 10 cm −2 ) compared to a bare SnO 2 NW memory device. The Er 2 O 3 capped SnO 2 device also exhibited good endurance over 500 programming/erasing cycles as well as good retention properties (measured for 10 3 s) with charge loss as low as 1.86%. The programme/erase process of the Er 2 O 3 capped SnO 2 device is explained with respect to a band diagram. The fabricated Er 2 O 3 capped SnO 2 NS is a Type-II heterostructure with Er 2 O 3 acting as a charge trapping layer. Such a heterostructure type is a good candidate for non-volatile memory applications.

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The Er2O3 nanowires (NWs) were synthesized on Si substrate by using glancing angle deposition technique inside E-beam evaporator. The field-emission gun scanning electron microscopy (FEG-SEM) images showed perpendicular and highly porous Er2O3 NWs with average diameter ∼50 nm and length ∼350 nm. The crystallinity of the Er2O3 NWs improved with annealing but degraded at higher temperature annealing at 900 °C. Transmission electron microscopy (TEM) images show the unsymmetrical NW growth and grain size enhancement with increasing annealing temperature. In addition, two-fold enhanced absorption was observed for as deposited as compared to the annealed samples. A low intense photoluminescence was obtained for the as deposited sample as compared to the annealed samples due to the presence of defects and dangling bonds. The as deposited Er2O3 NW also showed a hydrophobic surface property with a contact angle of as high as 107.4° due to the air trapped in between Er2O3 NWs and oxygen vacancies which turned to hydrophilic surface with contact angle 27° and 25° when annealed at higher temperature of 750 °C and 900 °C respectively.

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