Formation of high-mobility silicon—germanium structures by low-energy plasma enhanced chemical vapor deposition

Method for making a semiconductor heterostructure in a growth chamber (23) with gas inlet (26, 30), comprising the steps:

• forming a virtual substrate on a silicon substrate (11;
• 51;
• 61), comprising a graded Si1-xGex layer (12;
• 52;
• 62) followed by a Si1-xGex layer (13;
• 53;
• 63) with constant concentration of Ge, using a high-density, low-energy plasma enhanced chemical vapor deposition (LEPECVD) process with
• i. a growth rate above 2 nm/s,
• ii. a substrate temperature between 400° and 850° C., and
• iii. a total reactive gas flow at the gas inlet between 5 sccm and 200 sccm,
• forming an active region (14;
• 58;
• 69) on said virtual substrate comprising a Ge-channel (55;
• 65) and a modulation-doped layer (56;
• 64, 67) using a low-density, low-energy plasma enhanced chemical vapor deposition (LEPECVD) process by
• i. introducing hydrogen (H2) into the growth chamber (23) to act as a surfactant,
• ii. maintaining a substrate temperature between 400° and 500° C.,
• iii. introducing a dopant gas in a pulsed manner into the growth chamber (23) to provide for the modulation-doped layer (56;
• 64, 67).