We present a detailed analysis of near zero-energy Feshbach resonances in ultracold collisions of atom and molecule,taking the He–PH system as an example, subject to superimposed electric and magnetic static fields. We find that the electric field can induce Feshbach resonance which cannot occur when only a magnetic field is applied, through couplings of the adjacent rotational states of different parities. We show that the electric field can shift the position of the magnetic Feshbach resonance, and change the amplitude of resonance significantly. Finally, we demonstrate that, for narrow magnetic Feshbach resonance as in most cases of ultracold atom–molecule collision, the electric field may be used to modulate the resonance, because the width of resonance in electric field scale is relatively larger than that in magnetic field scale.
Etectroluminescence peaking at 1.3 μm is observed from high concentration boron-diffused silicon p^＋-n junctions. This emission is efficient at low temperature with a quantum efficiency 40 times higher than that of the band-to-band emission around 1.1 μm, but disappears at room temperature. The 1.3-μm band possibly originates from the dislocation networks lying near the junction region, which are introduced by high concentration boron diffusion.
