Minority carrier transport in p-ZnO nanowires

Abstract

In this work, we explore the minority carrier diffusion length in zinc oxide nanowires, using the electron beam-induced current technique. Systematic measurements as a function of temperature were performed on p-type, Sb-doped ZnO film, containing a 4 m thick nanowire layer. The minority carrier diffusion length exhibits a thermally activated increase with the energy of 74Ϯ 5 meV. Electron beam irradiation also causes the diffusion length increase with the activation energy of 247Ϯ 10 meV, likely related to Sb Zn-2V Zn acceptor-complex.

Impact of forward bias injection on minority carrier transport in p-type ZnO nanowires

“…2,3 Minority carrier transport has also been recently studied in p-type Sb doped ZnO nanowires subjected to electron beam irradiation. 6 It is also of interest that an increase in minority carrier diffusion length, similar to the electron beam irradiation effect, can be witnessed in p-type GaN and ZnO through forward bias electron injection in the epitaxial p-n homo-junctions. 1,13 In this paper, we report the impact of forward bias electron injection on minority carrier diffusion length in p-type Sb-doped ZnO nanowires at variable temperatures.…”

“…This forward bias injection-induced increase of L suggests that it comes from a similar origin to that of the electron beam irradiation-induced increase. 6 The effect of electron irradiation on the diffusion length can be attributed to the trapping of non-equilibrium electrons on the neutral acceptor levels (A 0 þ e À ! A À ).…”

“…This is in good agreement with our previous work on p-type ZnO nanowires, where the impact of electron beam irradiation on minority carrier transport was studied. 6 It has been theorized by Limpijumnong et al that the role of acceptors in size-mismatched Sb-impurity doped ZnO is accomplished by a Sb Zn -2V Zn complex, which is predicted to have an ionization energy of 160 meV. 8 While our value for activation energy (217 meV) is somewhat larger than the predicted value (160 meV), we can successfully rule out other Sb-related defects such as Sb o substitutional defects as well as the single vacancy Sb Zn -V Zn complex, due to their ionization energies being about an order of magnitude larger than our value.…”

Imaging transport in nanowires using near-field detection of light

“…Mobility measurements on holes in ZnO, however, have been limited by the challenges associated with p-type doping in this material. Recent EBIC measurements [22] on the collective response of a layer of nanowires in Sb-doped material indicated a room temperature value of $ 2.7 mm for L d , but it would be for minority carrier electrons if a high level of p-type doping has been achieved and therefore is not a direct comparison.…”