Diamond delta doped structures exhibiting ultra-sharp interfaces
Résumé
Boron delta-doping of diamond has appeared as a promising viable approach for the fabrication of high performance RF power transistors taking advantage of diamond properties. Here structures based on p-/p+/p- multilayers were synthesised on (100) HPHT Ib substrates using MPCVD. An original gas injector system was developed enabling to significantly improve the sharpness of both interfaces between p+ and p- layers with a good reproducibility. SIMS profiles recorded on the doping transients still demonstrate an asymmetry of the interface sharpness from 7nm/decade to 2nm/dec on the p-/p+ and the p+/p- interfaces, respectively. The observed differences are here explained and confirmed experimentally, and result from the combination of ion mixing with the effect of the surface roughness, thus limiting the SIMS resolution in depth. The MRI (Mixing Roughness Information) model then allows to evaluate the real value of the delta thickness achievable using this technique to 7 nm and the negative and positive gradients to identical values, namely of 1.4 nm/dec.
Mots clés
Diamond Delta Structures
Boron
Diamond
Substrates
Microwave theory and techniques
Radio frequency
Nonhomogeneous media
Doping
microwave power transistors
plasma CVD
radiofrequency integrated circuits
secondary ion mass spectroscopy
semiconductor doping
surface roughness
mixing roughness information
MRI model
ion mixing combination
SIMS profiles
secondary ion mass spectrometry
gas injector system
MPCVD
microwave-plasma-enhanced chemical vapor deposition
HPHT substrates
high pressure high temperature substrates
RF power transistors
boron delta-doping
ultrasharp interfaces
diamond delta doped structures
size 7 nm