Y-doped SnO₂ thin film transistors were successfully fabricated by means of sol-gel process. The effect of Y concentration on the structural, chemical, and electrical properties of sol-gel-processed SnO₂ films was investigated via GIXRD, SPM, and XPS; the corresponding electrical transport properties of the film were also evaluated. The dopant, Y, can successfully control the free carrier concentration by suppressing the formation of oxygen vacancy inside SnO₂ semiconductors due to its lower electronegativity and SEP. With an increase of Ywt%, it was observed that the crystallinity and oxygen vacancy concentration decreased, and the operation mode of SnO₂ thin film transistor changed from accumulation (normally on) to enhancement mode (normally off) with a positive V_th shift.

Sol-gel-processed Mg-doped SnO₂ thin-film transistors (TFTs) were successfully fabricated. The effect of Mg concentration on the structural, chemical, and optical properties of thin films and the corresponding TFT devices was investigated. The results indicated that an optimal Mg concentration yielded an improved negative bias stability and increased optical band gap, resulting in transparent devices. Furthermore, the optimal device performance was obtained with 0.5 wt% Mg. The fabricated 0.5 wt% Mg-doped SnO₂ TFT was characterized by a field effect mobility, a subthreshold swing, and I_on/I_off ratio of 4.23 cm²/Vs, 1.37 V/decade, and ~1 × 10⁷, respectively. The added Mg suppressed oxygen-vacancy formation, thereby improving the bias stability. This work may pave the way for the development of alkaline-earth-metal-doped SnO₂-based thin-film devices.

Sol-gel processed SnO₂ thin-film transistors (TFTs) were fabricated on SiO₂/p₊ Si substrates. The SnO₂ active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO₂ active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (SS), and increased threshold voltage (V_th), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO₂ TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm²/Vs, an SS of 1.99, an I_on/I_off value of ~4.0 × 10⁷, and showed enhancement mode operation and positive V_th, equal to 9.83 V.

In this paper, a highly efficient and compact 840 MHz class-F amplifier using E-pHEMT FET is implemented with the minimal footprints, where only the 2^nd and 3^rd harmonics is controlled to obtain the high efficiency within the harmonic control circuit. Compared to the transmission line, the discrete LC network is a more suitable solution to the small-sized implementation when it is carefully designed for the maximum performance. As such, this paper shows that the small-sized class-F PA can equally perform the ones with transmission lines for the harmonic control, and is more suitable for compact sized wireless terminal applications. The implemented power amplifiers have the peak efficiency of 81.2% with output power of 24.4 dBm.