Role of deep and shallow donor levels on n-type conductivity of hydrothermal ZnO

Abstract

International audienceThe residual n-type conductivity of O-polar hydrothermally grown ZnO single crystals and the role of annealing on the transport properties are assessed by temperature dependent Hall measurements on a wide 20-800 K temperature range. A deep level lying 250 meV below the conduction band is responsible for the residual n-type conductivity of unannealed samples. After annealing, a shallow donor level with 25 meV ionization energy becomes responsible for the sample conductivity in the room temperature range. Thanks to high temperature Hall measurement, the coexistence of the deep and the shallow level has been demonstrated in the case of annealed sample

Role of intrinsic and extrinsic defects in H implanted hydrothermally grown ZnO

“…Surface layer conductivity has been shown to be present in commercially available as received [81][82][83][84] as well as annealed ZnO wafers. 28,85,86 Furthermore, it has been shown by using variable field magnetotransport measurements that the surface layer might play a major role in lowering the mobility peak from 1100 cm 2 V À1 s À1 down to 400 cm 2 V À1 s À1 when TDH measurements are performed on highly compensated ZnO. 82 In our study, experimental evidence for the presence of residual surface conduction has been found only in C and C 0 , as can be seen in Fig.…”

Effects of nanoscale morphology and defects in oxide: optoelectronic functions of zinc oxide nanowires

“…Figure 3(c) shows the absorbance of ZnO NWs with a strong absorption peak located at 365 nm, which is attributed to the band gap (red curve) and without (black curve) thermal treatment at 400 °C. Besides a band-edge emission at 384 nm, we observed a broad visible emission around 560nm which can be attributed to the surface oxygen vacancies and other defects such as oxygen interstitials and zinc vacancies (32)(33)(34)(35)(36) known as deep donors. However, the visible emission was significantly reduced after the thermal treatment (red curve in Figure 3(d)).…”

“…(34-36, 39, 40). By contrast, between the disks two dimensional ZnO NShs grow with low crystallinity (TEM image in the top inset of Figure 4(a)) exhibiting a strong broad yellow band centered at 547 nm, which is associated to the zinc vacancies (34,36,40). A very weak band-edge emission around 400 nm is observed.…”

Piezoelectric Nanogenerator Based on ZnO Nanomaterials

“…Also, ZnO is a biosafe and biocompatible material [5]. In its unintentional doping, zinc oxide grows as an n-type material with many shallow donor levels [6]. Although ZnO is known to researchers since the 1930s [7], the interest in ZnO has been ϐluctuating despite many excellent properties of this material.…”

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