We demonstrated a device with a unique planar architecture using a novel approach for obtaining low arsenic doping concentrations
in long-wavelength (LW) HgCdTe on CdZnTe substrates. HgCdTe materials were grown by molecular beam epitaxy (MBE). We fabricated
a p-on-n structure that we term P+/π/N+ where the symbol “π” is to indicate a drastically reduced extrinsic p-type carrier concentration (on the order of mid 1015 cm−3); P+ and N+ denote a higher doping density, as well as a higher energy gap, than the photosensitive base π-region. Fabricated devices
indicated that Auger suppression is seen in the P+/π/N+ architecture at temperatures above 130 K and we obtained a saturation current on the order of 3 mA on 250-μm-diameter devices at 300 K with Auger suppression. Data shows that about a 50% reduction in dark current is achieved at 300 K
due to Auger suppression. The onset of Auger suppression voltage is 450 mV at 300 K and 100 mV at 130 K. Results indicate
that a reduction of the series resistance could reduce this further. A principal challenge was to obtain low p-type doping levels in the π-region. This issue was overcome using a novel deep diffusion process, thereby demonstrating successfully
low-doped p-type HgCdTe in MBE-grown material. Near-classical spectral responses were obtained at 250 K and at 100 K with cut-off wavelengths
of 7.4 μm and 10.4 μm, respectively. At 100 K, the measured non-antireflection-coated quantum efficiency was 0.57 at 0.1 V under backside illumination.
Received November 7, 2007; accepted March 19, 2008 相似文献
The dynamic rotor behavior is significantly affected by the stiffness and damping characteristics of the bearings. Therefore, it is important to identify these bearing parameters. For active magnetic bearings (AMBs), these bearing parameters not only could be identified from rotor dynamic response, but also from electrical control system transfer function. Some identification works from rotor dynamic response have been reported, but identification from electrical control system transfer function is relatively few. In this paper, we deduced the equivalent stiffness and damping expressions with electrical control system transfer function for rotor AMBs and identified these values from electrical control system model. To evaluate the identified results, previous reported results from rotor dynamic response is employed for comparison. We found that for the stiffness, a complete and precise electrical control model will obtain relatively consistent values; however, for the damping, the accurate electrical control model is still not enough and the eddy current loss should be included.
A new acceptor–donor–acceptor‐structured nonfullerene acceptor ITCC (3,9‐bis(4‐(1,1‐dicyanomethylene)‐3‐methylene‐2‐oxo‐cyclopenta[b]thiophen)‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d′:2,3‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]‐dithiophene) is designed and synthesized via simple end‐group modification. ITCC shows improved electron‐transport properties and a high‐lying lowest unoccupied molecular orbital level. A power conversion efficiency of 11.4% with an impressive VOC of over 1 V is recorded in photovoltaic devices, suggesting that ITCC has great potential for applications in tandem organic solar cells. 相似文献
The performance of organic photovoltaics (OPVs) has rapidly improved over the past years. Recent work in material design has primarily focused on developing near‐infrared nonfullerene acceptors with broadening absorption that pair with commercialized donor polymers; in the meanwhile, the influence of the morphology of the blend film and the energy level alignment on the efficiency of charge separation needs to be synthetically considered. Herein, the selection rule of the donor/acceptor blend is demonstrated by rationally considering the molecular interaction and energy level alignment, and highly efficient OPV devices using both‐fluorinated or both‐nonfluorinated donor/acceptor blends are realized. With the enlarged absorption, ideal morphology, and efficient charge transfer, the devices based on the PBDB‐T‐F/Y1‐4F blend and PBDB‐T‐F/Y6 exhibit champion power conversion efficiencies as high as 14.8% and 15.9%, respectively. 相似文献