Deeprecessed AlGaNGaN HEMTs

1

• Deep-recessed AlGaN/GaN HEMTs
• MBE
• Epitaxial structure
• DC and pulsed I-V
• Power performance
• MOCVD
• Stability
• Epitaxial field-plate
• MBE vs. MOCVD
• Progress of RGA endpoint detection

2
Deep-recessed HEMTs by MBE

• MBE growth
• Growth temperature 720C Carbon-free buffer
• Lower growth temperature than MOCVD less thermal
  stress flexible graded AlGaN thickness and
  Al composition
• Allows the optimization of charge density for
  better dispersion reduction and power performance

3
Power performance

• Good power performance achieved without
  passivation (LG0.7mm)

4
Stability
D
S
G
150nm Al0.05Ga0.95N
100nm graded AlGaNSi
40nm UID Al0.22Ga0.78N
0.7nm AlN
S.I. GaN (Grown by MOCVD)

• Test Condition
• 150C, 24-hour RF stress at 2dB gain compression
  point
• Stability
• Gain net change of 0.3dB
• Drain current constant
• Gate leakage reduced, due to the annealing affect

4
5
Epitaxial field-plate

• Grown by MBE on SiC
• Gate leakage increase with longer LFP
• Field-plate on AlGaN is leaky
• Power independent on LFP

• Grown by MOCVD on SiC
• Gate leakage decrease with longer LFP
• Power dispersion appears with field-plate

6
RGA endpoint detection

• Progress
• Cleanroom is being moved
• RGA was connected to the Panasonic ICP etcher
• Initial GaN etch test showed the Ga peak was
  detected shortly after the plasma was on.

• Future work
• RGA endpoint detection
• Improve signal-to-noise ratio
• Investigate AlGaN and InGaN etch and use them as
  mark layers
• Develop detectable low-etch-rate gate recess

• Deep-recessed HEMT
• Hybrid device thick cap and SixN
• Both contribute to dispersion suppression
• Reduce gate leakage of FP devices SixN below the
  FP