Transport Properties and Finite Size Effects in β-Ga2O3 Thin Films

Abstract

Thin films of the wide band gap semiconductor β-Ga2O3 have a high potential for applications in transparent electronics and high power devices. However, the role of interfaces remains to be explored. Here, we report on fundamental limits of transport properties in thin films. The conductivities, Hall densities and mobilities in thin homoepitaxially MOVPE grown (100)-orientated β-Ga2O3 films were measured as a function of temperature and film thickness. At room temperature, the electron mobilities ((115 ± 10) cm2/Vs) in thicker films (>150 nm) are comparable to the best of bulk. However, the mobility is strongly reduced by more than two orders of magnitude with decreasing film thickness ((5.5 ± 0.5) cm2/Vs for a 28 nm thin film). We find that the commonly applied classical Fuchs-Sondheimer model does not explain sufficiently the contribution of electron scattering at the film surfaces. Instead, by applying an electron wave model by Bergmann, a contribution to the mobility suppression due to the large de Broglie wavelength in β-Ga2O3 is proposed as a limiting quantum mechanical size effect.

Interface Trap-Induced Temperature Dependent Hysteresis and Mobility in β-Ga2O3 Field-Effect Transistors

“…The interface scattering became predominant over any other scatterings including ionized impurity scattering, and mobility steeply decreased. This can also be envisioned by the strong gate bias dependence of the channel mobility at low temperature, as discussed earlier (Figure 5b), and the previous reports of strong mobility degradation by the surface effects in β-Ga 2 O 3 thin-films at low temperatures [33]. We also carried out a time-domain analysis on the capture and release of charges by the traps at the interface by measuring the transient response to observe the behaviors of the traps [34].…”

Enhanced Charge Transfer in Atom‐Thick 2H–WS2 Nanosheets’ Electron Transport Layers of Perovskite Solar Cells

“…Meanwhile, the bulk properties of the ETL or perovskite, such as thin‐film thickness, bulk film structure, etc., might have a certain role in this process. Nevertheless, in most studies, [ 37 ] they mainly determine the transportation characteristic of the carrier to the electrode. These phenomena were verified by the FF and V oc properties of the devices of which it decreases with the increase in WS 2 ETL thickness (Figure 3C‐E), reflecting the increase in resistance related to the loss due to the increase in trap density or energetic disorder properties as WS 2 thickness increases.…”

Модифікація електронних властивостей надтонких плівок β-Ga2O3 механічними впливами

“…According to previous studies, the characteristics of Ga 2 O 3 -based devices are substantially affected by the mechanical state of Ga 2 O 3 [20]. An elastic field in a device arises in the course of thermal growing of Ga 2 O 3 , as well as due to a grating mismatch with other contacting materials, which is responsible for the thermal stability and transport properties of the material [21][22][23][24][25][26][27][28][29][30][31].…”