arXiv subjects

B. S. Zhang

Publications and source records attributed to B. S. Zhang.

3 recordsLinked to original sources

arXiv2012

Spin Hall Angle Quantification from Spin Pumping and Microwave Photoresistance

We present a method to quantify the spin Hall angle (SHA) with spin pumping and microwave photoresistance measurements. With this method, we separate the inverse spin Hall effect (ISHE) from other unwanted effects for permalloy/Pt bilayers using out-of-plane microwave excitation. Through microwave photoresistance measurements, the in- and out-of-plane precessing angles of the magnetization are determined and enabled for the exact determination of the injected pure spin current. This method is demonstrated with an almost perfect Lorentz line-shape for the obtained ISHE signal and the frequency independent SHA value as predicted by theory. By varying the Pt thickness, the SHA and spin-diffusion length of Pt is quantified as 0.012 (0.001) and 8.3 (0.9) nm, respectively.

cond-mat.mes-hall↗

arXiv2012

Probing and modelling the localized self-mixing in a GaN/AlGaN field-effect terahertz detector

In a GaN/AlGaN field-effect terahertz detector, the directional photocurrent is mapped in the two-dimensional space of the gate voltage and the drain/source bias. It is found that not only the magnitude, but also the polarity, of the photocurrent can be tuned. A quasistatic self-mixing model taking into account the localized terahertz field provides a quantitative description of the detector characteristics. Strongly localized self-mixing is confirmed. It is therefore important to engineer the spatial distribution of the terahertz field and its coupling to the field-effect channel on the sub-micron scale.

cond-mat.mes-hall↗

arXiv2005

Comparison of the properties of GaN grown on complex Si-based structures

With the aim of investigating the possible integration of opto-electronic devices, epitaxial GaN layers have been grown on Si(111) SOI and on Si/CoSi2/Si(111) using metalorganic chemical vapor deposition. The samples are found to possess a highly oriented wurtzite structure, a uniform thickness and abrupt interfaces. The epitaxial orientation is determined as GaN(0001)//Si(111), GaN[1120]//Si[110] and GaN[1010]//Si[112], and the GaN layer is tensily strained in the direction parallel to the interface. According to Rutherford backscattering/channeling spectrometry and (0002) rocking curves, the crystalline quality of GaN on Si(111) SOI is better than that of GaN on silicide. Room-temperature photoluminescence of GaN/SOI reveals a strong near-bandedge emission at 368 nm (3.37 eV) with an FWHM of 59 meV.

cond-mat.mtrl-sci↗