Selective growth of Si/SiGe resonant tunneling diodes by atmospheric pressure chemical vapor deposition

Abstract

Atmospheric pressure chemical vapor deposition is used to grow p-type Si/Si1-xGex double-barrier resonant tunneling structures on unstrained substrates, with a Si0.75Ge0.25 well clad by Si barriers. The current-voltage I(V) characteristics at T=77 and 4.2 K exhibit current peaks and negative differential resistance regions corresponding to resonant tunneling through well-resolved heavy- and light-hole subbands in the well. Device quality is comparable to Si/SiGe resonant tunneling structures grown by molecular beam epitaxy. The in situ substrate cleaning and selective growth capabilities of atmospheric pressure chemical vapor deposition are used for the first successful selective growth of resonant tunneling structures through an oxide mask. The resulting diodes exhibit good resonant tunneling characteristics. The selective growth process is promising for the fabrication of small vertical heterostructure devices.