Nanowire Technology

Nanowire Technology

More technical news from our US colleagues about the use of changing the morphology of gallium phosphide nanocomposites significantly enhancing its optical and electrical properties

Recent progress in III-V type semiconductors gained significant interest because of their unique physical and electronic properties. III-V based alloys like 93-3123, CAS12063-98-8 Gallium Phosphide (GaP, 99.999%-Ga), or 93-3103, CAS1303-00-0  Gallium Arsenide (GaAs 99.9999%-Ga), systems have shown high efficiencies in a variety of applications.

In contrast to GaAs (band gap 1.42 eV), which is a major component of most efficient solar cell to date, GaP has larger band gap (2.26 eV) which does not allow maximum solar energy adsorption. On the other hand, due to the high band gap, GaP is an excellent candidate for multi-junction systems (e.g. InGaP or AlInGaP), which makes improved solar energy conversion possible [1].

An alternative way to avoid external bias and overcome the limitations of energy adsorption is to apply nanowire technology. GaP nanowires grown on wurtzite slightly decrease band gap to 2.1 eV.  This makes an increase in the absorption of the solar spectrum possible. Semiconductors with a band gap between 1.7 and 2.2 eV allow photoelectrochemical conversion of solar energy to hydrogen fuel by water splitting. Furthermore, by modifying the GaP surface with a minimum amount of platinum, the yield of very clean, CO free, fuel hydrogen was boosted by a factor of ten [2].

(a) Scanning electron microscopy image of a typical array of GaP nanowires defined by nano imprint lithography. Scale bar, 400 nm. (b) High-resolution TEM image of a typical p-type GaP nanowire with wurtzite crystal structure; scale bar, 5 nm.

GaP is also used for light-emitting diode (LED) devices. Depending on the dopants, GaP emits in green and red spectrum range. Undoped GaP generates green light at a wavelength of 555 nm, nitrogen doped GaP emits yellow-green light at 565 nm and  zinc oxide doped GaP emits red light spectrum at a wavelength of 700 nm. To create p-n junctions, sulfur or tellurium are used for n-type semiconductors and zinc is used as a dopant for the p-type semiconductora gallium