We report on the fabrication and optoelectronic properties of p‐n heterojunction arrays of p+‐type Si and aligned n‐type SnO2 nanowires with high rectification ratios of >104 at ±15 V. The electrical stability of the p‐n heterojunction devices was improved by coating the junction with poly(methylmethacrylate) to minimize the degradation of the interface layer at the junction. As a photodiode an enhanced UV photosensitivity higher than 102 was recorded under reverse bias. Using a large forward bias in the light‐emitting diode mode white light was emitted from the large‐scale heterojunction devices with at least three broad peaks in the visible range, which can be attributed to the interband transitions of the injected electrons or holes mediated by an interfacial SiO2 layer with a contribution of trap‐level energies. These results indicate the high potential of Si/SnO2 nanowires heterojunctions as optoelectronic devices with proper tuning of the recombination center at the junctions.

p-n hetero-junction diode arrays were fabricated using specific direct techniques for the transfer of p-type single walled carbon nanotubes (SWCNTs) and aligned n-type SnO₂ nanowires (NWs) onto a patterned substrate surface. Their electronic and optoelectronic properties were characterized. Perpendicular crossings of the p- and the n-channels with each other were confirmed by transfer characteristics with respect to the bottom gate. The resulting diode showed a good rectifying behavior with a rectification ratio of over 10² at ±5 V, where the equivalent circuit model of a serially connected diode and resistor was used for analysis of the electrical properties. Both the forward and the reverse currents were observed to increase with the application of a positive gate bias, indicating an n-type gate dependence. Under a forward bias, the dominant contribution of the SnO₂ NW channel to the total resistance of the equivalent model is attributed to the n-type gate dependence since the resistance of the n-channel increased with a negative gate bias, resulting in the decrease of the forward current. Under a reverse bias, positive gate increased the concentration of valence electrons in the SWCNTs, enhancing direct tunneling to the conduction band of the SnO₂ NWs. High sensitivity to UV irradiation under the reverse bias was also demonstrated with a photosensitivity over 10², suggesting potential applicability of the hetero-junction diodes in optoelectronic devices.

Hetero-junction array of p+-Si/n-ZnO nanowires (NWs) was fabricated via contacting of aligned ZnO NWs onto a patterned p+-Si substrate. Current-voltage (I-V) measurement on the p-n junction showed a rectification behavior with a high rectification ratio of 104 at ±3 V. In addition, the enhancement of forward current as well as the decrease of the turn-on voltage was observed with the application of negative gate bias and noticeable p-type gate dependence, which was explained in terms of asymmetric shift of the Fermi levels with gate bias in the suggested energy band diagram. Such formed hetero-junction devices showed strong UV sensitivity of 2 × 104 under reverse bias of −3 V and electroluminescence in both UV and visible ranges, suggesting its potential applicability in optoelectronic devices.