Effect of Si/Si _1-yC _y/Si barriers on the characteristics of Si _1-xGe _x/Si resonant tunneling structures

P-type double barrier resonant tunneling diodes (RTD) with the single Si _0.6Ge _0.4 quantum well and double Si _0.6Ge _0.4 spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si _1-yC _y layer on the characteristics of the devices was shown by comparing the current-voltage (I - V) characteristics of RTD's of the barriers of Si layers with that of Si/Si _1-yC _y/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/Si _1-yC _y/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/Si _1-yC _y/Si barriers. The possible mechanism for the observed I-V characteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si _1-yC _y layers in the Si/Si _1-yC _y/Si barriers.