An investigation into the conversion of In2O3 into InN nanowires

Abstract

Straight In 2 O 3 nanowires (NWs) with diameters of 50 nm and lengths ≥2 μm have been grown on Si(001) via the wet oxidation of In at 850°C using Au as a catalyst. These exhibited clear peaks in the X-ray diffraction corresponding to the body centred cubic crystal structure of In 2 O 3 while the photoluminescence (PL) spectrum at 300 K consisted of two broad peaks, centred around 400 and 550 nm. The post-growth nitridation of In 2 O 3 NWs was systematically investigated by varying the nitridation temperature between 500 and 900°C, flow of NH 3 and nitridation times between 1 and 6 h. The NWs are eliminated above 600°C while long nitridation times at 500 and 600°C did not result into the efficient conversion of In 2 O 3 to InN. We find that the nitridation of In 2 O 3 is effective by using NH 3 and H 2 or a two-step temperature nitridation process using just NH 3 and slower ramp rates. We discuss the nitridation mechanism and its effect on the PL.

A systematic study of the nitridation of SnO2 nanowires grown by the vapor liquid solid mechanism

“…No peaks related to Sn make their appearance despite the presence of H 2 . Finally we find that employing a two step temperature nitridation process involving NH 3 : 20% H 2 and slow ramp rates as listed in Table 1 was successfully achieved by employing the nitridation strategies described above [23,24]. The post-growth nitridation of b-Ga 2 O 3 and In 2 O 3 NWs proceeds via a reduction to Ga 2 O and In 2 O, respectively, which react with NH 3 .…”

“…In addition we have grown and investigated the optical properties of metal oxide (MO) nanowires, i.e. SnO 2 , In 2 O 3 and b-Ga 2 O 3 [20][21][22] NWs and their conversion into nitrides via post-growth nitridation using NH 3 and H 2 [23,24]. We found that it is possible to obtain InN and GaN NWs via the postgrowth nitridation of In 2 O 3 and Ga 2 O 3 NWs, respectively, so here we have undertaken a systematic investigation into the nitridation of SnO 2 NWs in order to improve our understanding of Sn 3 N 4 and enable further investigations on its potential as a material for solar cell devices.…”

Structural properties of SnO2 nanowires and the effect of donor like defects on its charge distribution

“…Metal oxide (MO) semiconductor NWs are in particular attractive for the fabrication of sensors, solar cells, electronic and optoelectronic nanoscale devices. In the past we have investigated a broad range of MO NWs such as ZnO 1 In 2 O 3 2, 3 Ga 2 O 3 4 and SnO 2 NWs 5, 6. The latter are attractive since they may be grown with uniform diameters of 50 nms and lengths up to 100 µm by the reaction of Sn with O 2 on Au/Si(001) thereby avoiding the incorporation of other impurities such as C which is included during carbothermal reduction synthesis of MO NWs.…”

The nitridation of ZnO nanowires

“…solar cells, especially as it is possible to tune their energy band gap over a wide range like for instance in InGaN [13]. Recently, we also demonstrated the conversion of In 2 O 3 [14] and Ga 2 O 3 NWs [15] into their respective nitrides, i.e. InN and GaN, using different post growth nitridation strategies including NH 3 and H 2 .…”

“…Therefore, we have undertaken a systematic investigation into the post growth nitridation and conversion of ZnO NWs into Zn 3 N 2 NWs, thereby complementing our earlier investigations on the nitridation of other MO NWs [14,15]. ZnO NWs with diameters of 50 to 250 nm, lengths up to 10 μm and a hexagonal wurtzite crystal structure were obtained with a high yield and uniformity not only on ≈1 nm Au/Si(001) and 1 nm Au/quartz via reactive vapour transport, but also on plain Si(001) at 550°C.…”