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The Effect of Introducing Optical Blanking on GaN Epitaxy Using Pulsed Laser Deposition Technology
Author(s) -
Kodama Kazuki,
Ueda Daisuke
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900517
Subject(s) - blanking , materials science , ohmic contact , optoelectronics , laser , duty cycle , contact resistance , picosecond , pulsed laser deposition , sheet resistance , epitaxy , optics , thin film , voltage , composite material , electrical engineering , nanotechnology , computer science , physics , layer (electronics) , computer vision , engineering
The optical blanking operation of pulsed laser deposition (PLD) using a picosecond laser enables the dramatic reduction of sheet resistance with excellent uniformity for the regrowth of heavily Ge‐doped GaN films. Attained carrier density exceeds over 3.5 × 10 20 cm −3 , which is good enough to achieve nonalloy ohmic contact. The obtained contact resistance is 0.05 Ω mm regardless of the overlaying metal. Blanking duty ratio for the pulse‐mode operation can be simply controlled by rotating the half‐wave plate outside the vacuum chamber. By introducing the blanking mode, the complete elimination of the Ga droplet is achieved even at a growth temperature of 500 °C, showing a decrease in sheet resistance. It is confirmed that the ohmic characteristics remain unchanged on annealing treatment up to 300 °C. The proposed growth technique using laser blanking is free from mechanical shutter; therefore, the technique has superior repeatability in GaN epitaxy. It is believed the present optical blanking operation is a useful technique for the industrialization of practical GaN devices.