Strain induced photoluminescence from silicon and germanium nanowire arrays

Abstract

The optical properties of silicon and germanium nanowires grown within the pores of hexagonal mesoporous silica matrices have been characterised by ultraviolet absorption and photoluminescence (PL) spectroscopy. A clear blue-shift in the PL of the semiconductor composite materials was observed as the diameter of the nanowires decreased from 85 to 22 A ˚.Powder X-ray diffraction revealed that, as the diameter of the confined nanowires decreased, the strain on the crystallographic structure of the nanowires increased, due to escalating lattice expansion, resulting in a shift in the PL maximum to higher energies. The ability to manipulate the optical properties in templated semiconductor nanowires, through strain engineering, has important implications for the design of future optical devices.

Strain-modulated electronic properties of Ge nanowires: A first-principles study

“…Theoretically, researchers found that the band gap of Ge nanowires are dependent on several factors, such as size, [19][20][21] crystalline orientation, [20][21][22] surface chemistry, 22,23 and doping. 22,24 However, there is only very limited study 11 of strain effects on electronic properties of Ge nanowires.…”

“…This effect has been observed, for example, in photoluminescence (PL) studies, and found to exhibit substantial blue-shift of emission with reduction of nanowire diameter. For instance, Audoit et al, 11 have grown Ge nanowires in the size range of 22 Å -85 Å using supercritical fluid methods. They observed a clear blue-shift in the PL of the nanowires compared to the Ge band gap of 0.66 eV.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] They are expected to play important roles as both interconnects and functional components in future nanoscale electronic and optical devices, such as lightemitting diodes (LEDs), 3 ballistic field-effect transistors (FETs), 4, 5 inverters, 6 and nanoscale sensors. 7,8 Therefore, it is of great importance to study electronic properties of those nanowires, such as band gap, density of state and effective mass of charge carriers.…”

Effects of surface oxide formation on germanium nanowire band-edge photoluminescence

“…[6][7][8][9][10] Other studies have mainly concerned visible PL from Ge nanocrystals embedded in various oxide matrices, and the role of the defects at the nanocrystal/ matrix interface or in the matrix itself. [11][12][13][14][15][16] In the case of Ge NWs, there are few reports of PL detected for band-to-band transitions in such nanowires, 17 due to the difficulty of detecting emission from unpassivated Ge NWs, which results from carrier trapping and nonradiative recombination. Among these, coherently strained Ge core/ SiGe shell nanowires exhibiting strong and bulk-like bandedge PL have been reported recently.…”

Lumineszcencia centrumok kialakítása és spektrális jellemzése nanogyémántban

“…Ez arra utal, hogy más folyamatok is befolyásolják a ZPL csúcshelyzetét. Egy lehetséges magyarázat lehet a kvantum pöttyöknél és kvantum gödröknél, valamint nanohuzaloknál megfigyelt tilos sáv kiszélesedés, ami ezen anyagok szerkezeti sajátosságaival áll kapcsolatban [60,61]. A nanoméret miatt ezen szerkezetek optikai tulajdonságai érzékenyebbek a szerkezeti hibákra, melyek torzíthatják a sávhatárokat.…”