Negative differential resistance (NDR) was observed in the dc photocurrent-reverse bias characteristics at 1.55 μm wavelength of a planar InP/InGaAs/InP double-heterojunction p-i-n photodiode, which is designed for high-speed operation. In the bias range of measurements, two NDR regions can be observed, which are suggested to be mainly caused by the drop of average electron velocities in both the InGaAs absorption and InP buffer layers, i.e., the transferred electron effect. For providing evidence, power dependence of these NDR regions was investigated. Besides, another high-responsivity p-i-n photodiode was fabricated and characterized for comparison.

Trifluoromethane-containing plasma is used to passivate the mesa surfaces and suppresses the surface leakage current of GaN p-i-n rectifiers. Reduction of surface leakage enhances the reverse blocking voltage by 25% measured at J = 1 A/cm 2 . Differential forward resistances of control samples and plasma-treated ones are 0.65 and 0.49 m -cm 2 , respectively, and an excellent Baliga's figure-of-merit of more than 800 MW/cm 2 , as compared with the conventional 545 MW/cm 2 , is achieved for GaN diodes fabricated on sapphire substrates.

No abstract

No abstract