Growth of highly resistive Ga‐polar GaN by LP‐MOVPE

Abstract

Electrical characteristics of 1.3 µm thick GaN films were investigated with respect to the polar type. Unintentionally doped N-polar GaN grown on nitrided sapphire substrates had a hexagonal facetted morphology and consistently exhibited a high n-type conductivity with a sheet resistance of ~10 Ω/sq, corresponding to a carrier concentration on the order of 10 19 cm -3 . In contrast, Ga-polar GaN films grown on low temperature AlN buffer layers showed a high sheet resistance of ~109 Ω/sq. GaN films of mixed polarity exhibited sheet resistance in-between the two extreme values obtained for polarity pure films. The results of this work show that the existence of N-polar domains (even on the nano-scale) in an otherwise Ga-polar matrix significantly decreases the insulating properties of unintentionally doped GaN films.

Influence of gallium supersaturation on the properties of GaN grown by metalorganic chemical vapor deposition

“…The growth process was performed as follows: after the substrate treatments consisting of H 2 annealing at 1100°C for 7 min and nitridation at 940°C for 4 min, a 10 nm thick AlN NL was grown at 600°C and then annealed at the GaN growth temperature of 1050°C in order to obtain highly resistive Ga-polar film. 19,20 After the annealing process, GaN growth was carried out under two different diluent gases, either N 2 or H 2 . A V/III ratio of 100 was established by flowing 36 mol/ min of TEG and 0.4 slm ͑li-ters per minute at standard temperature and pressure͒ of ammonia under a total flow rate of 7.5 slm.…”

Implementation of the GaN lateral polarity junction in a MESFET utilizing polar doping selectivity

“…A second ammonia‐annealing step for 11 min under an ammonia partial pressure of 10 Torr was performed prior to the GaN film growth. It was previously observed that the corresponding GaN films grown without performing these last two steps in the described way had properties of mixed‐polarity films 11. The GaN film was grown to a thickness of 1.3 µm followed by a 50 nm thick Si:GaN film for the channel.…”

AlGaN/GaN Heterostructures Electrical Performance by Altering GaN/Sapphire Buffers Growth Pressure and Low‐Temperature GaN Interlayers Application

“…It is well known that growth pressure has a great impact on the GaN buffer resistivity in MOVPE technology of AlGaN/GaN heterostructures. [20][21][22][23] We have checked whether it is possible to decrease 2DEG's resistivity while maintaining good insulation of GaN buffer at higher growth pressures.…”