Application

GaN-on-Si

One thin MST layer under the GaN stack: a better GaN crystal for power, and low-loss, highly linear silicon for RF.

Applications

Leading Logic DRAM 3D NAND Analog & Power GaN-on-Si RF-SOI Whitepapers All applications

GaN-on-Si

Power GaN-on-Si RF GaN-on-Si

How MST helps

A thin MST layer under the nucleation layer

MST is grown on the Si(111) substrate before the AlN nucleation layer. It improves the GaN crystal grown on top, and it blocks aluminium and gallium from doping the silicon, the cause of RF loss in GaN-on-Si.

Where MST sits in a GaN-on-Si stackOn the Si(111) substrate, under the AlN nucleation layer.

Power GaN-on-Si · silicon

A better GaN crystal on silicon

Lattice mismatch between GaN and silicon creates dislocations. On a high-performance baseline stack, MST cut the X-ray peak width by more than 20%, with the same epi recipe.

GaN crystal quality: X-ray (0002) peak widthFWHM in arcsec — lower is better

Reference: GaN on Si(111)GaN on MST on Si(111)

Same GaN stack, same recipe

650

510

MST: 510 vs 650 arcsec — more than 20% better GaN crystal quality.

Texas State University baseline RF GaN stack; reference 650 ± 10 arcsec. Similar gains in the (10-14) peak and the AlN layer.

GaN buffer defects: control vs MSTCross-section TEM, same epi recipe and imaging conditions.MST: fewer dislocations in the GaN buffer.

Partners have also measured lower leakage in lateral HEMTs on MST, which supports higher-voltage operation.

RF GaN-on-Si · silicon

GaN-on-Si joins mainstream RF

Aluminium and gallium leak into the silicon and form a parasitic channel: the main source of RF loss and distortion. MST blocks them, cutting that charge by more than 10×.

>10×

less parasitic interface charge (spreading-resistance profiling)

Silicon

16 kΩ·cm

effective resistivity at 900 MHz, vs ≈1 kΩ·cm typical for GaN-on-Si

Silicon

≈1000×

lower H2 and H3 distortion power than the reference wafer

Silicon

>15×

lower H2 than the best published GaN-on-Si, at >2× its resistivity

Silicon

Third-order intermodulation (IM3) vs output power — measuredMST: about 8 dB more output power at equal IM3, on the SiC curve: SiC-class linearity on high-resistivity silicon.

~8 dB

higher output power at equal IM3 than the baseline GaN-on-Si substrate

Silicon

The MST-enhanced silicon substrate solves the linearity problem: its IM3 curve sits on the SiC reference, at a silicon-substrate cost.

Against RF-SOI substrates, MST GaN-on-Si has lower H2 than Soitec's eSi90 trap-rich substrate and comes close to eSi100. At +35 dBm input it is even more competitive.

Gallium SIMS: GaN/AlN on Si(111), reference vs MSTMST: 2–3× less gallium in the top 300 nm of silicon (same wafers as the RF tests).

Substrate-level measurements on coplanar-waveguide test structures, thin GaN/AlN test stack, best-performing MST wafer; device-level (HEMT) data is not yet available. GaN growth by Texas State University; RF characterization by Incize.

Learn more: whitepapers & publications

Work with us

Partner with Atomera

Evaluate MST in your own process and devices with Atomera's engineering team.