In this paper, a high-quality sputtered-GeSn layer on Ge (100) with a Sn composition up to 7% was demonstrated. The crystallinity of the GeSn layer was investigated via high-resolution X-ray diffraction (HR-XRD) and the strain relaxation degree of the GeSn layer was evaluated to be approximately 50%. A novel method was also proposed to evaluate the averaged threading dislocation densities (TDDs) in the GeSn layer, which was obtained from the rocking curve of GeSn layer along the (004) plane. The photoluminescence (PL) measurement result shows the significant optical emission (1870 nm) from the deposited high-quality GeSn layer. To verify whether our deposited GeSn can be used for optoelectronic devices, we fabricated the simple vertical p-i-n diode, and the room temperature current–voltage (I–V) characteristic was obtained. Our work paves the way for future sputtered-GeSn optimization, which is critical for optoelectronic applications.

No abstract

Single-crystalline GePb alloys have been successfully achieved by implanting Pb into Ge, followed by rapid thermal annealing under N 2 atmosphere. The high crystallinity and the thickness of around 20 nm of the GePb alloys was determined by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. The root-mean-square value of the as-implanted GePb sample is evaluated to be 1.25 nm in the 5 × 5 um scan area, which indicates a rather smooth surface. After being annealed at 400 • C, the result of a selected area electron diffraction pattern suggested that a single-crystalline alloy film was formed for the first time. The Pb composition of this sample is approximately 0.23% according to the x-ray photoelectron spectroscopy results. This value corresponds with the measurement result of the secondary ion mass spectroscopy. In addition, mobility enhancement in GePb/Ge samples has been identified by temperature-dependent Hall measurement, which indicates GePb alloys have great potential to be a promising high-mobility channel material for future monolithic optoelectronics integration application.

No abstract

We report the radio frequency characteristics of the diamond metal-oxide-semiconductor field effect transistor with MoO3 gate dielectric for the first time. The device with 2-μm gate length was fabricated on high quality polycrystalline diamond. The maximum drain current of 150 mA/mm at VGS = -5 V and the maximum transconductance of 27 mS/mm were achieved. The extrinsic cutoff frequency of 1.2 GHz and the maximum oscillation frequency of 1.9 GHz have been measured. The moderate frequency characteristics are attributed to the moderate transconductance limited by the series resistance along the channel. We expect that the frequency characteristics of the device can be improved by increasing the magnitude of gm, or fundamentally decreasing the gate-controlled channel resistance and series resistance along the channel, and down-scaling the gate length.