A technology for the monolithic integration of resonant tunneling diodes （RTDs） and high electron mobility transistors （HEMTs） is developed. Molecular beam epitaxy is used to grow an RTD on a HEMT structure on GaAs substrate. The RTD has a room temperature peak-to-valley ratio of 5.2 ： 1 with a peak current density of 22. 5kA/cm^2. The HEMT has a 1μm gate length with a - 1V threshold voltage. A logic circuit called a monostable-to-bistable transition logic element （MOBILE） circuit is developed. The experimental result confirms that the fabricated logic circuit operates successfully with frequency operations of up to 2GHz.
A high performance AlAs/In0.53 Ga0.47 As/InAs resonant tunneling diode （RTD） on InP substrate is fabricated by inductively coupled plasma etching. This RTD has a peak-to-valley current ratio （PVCR） of 7. 57 and a peak current density Jp = 39.08kA/cm^2 under forward bias at room temperature. Under reverse bias, the corresponding values are 7.93 and 34.56kA/cm^2 . A resistive cutoff frequency of 18.75GHz is obtained with the effect of a parasitic probe pad and wire. The slightly asymmetrical current-voltage characteristics with a nominally symmetrical structure are also discussed.
