LED Wafer on Silicon

LED Wafer on Silicon

PAM-XIAMEN, an epi-provider for GaN LED on Si, can offer high performance blue and green light-emitting diode prototypes that grow 2”, 4”, 6” and 8” gallium nitride (GaN) layers based on LED wafer structure on silicon substrate as well as sapphire substrates. Silicon is a low-cost compared with sapphire substrates, and large diameter silicon wafer processing is already popular in the semiconductor market, with the possibility of mass LED manufacturing. For more details about the LED wafer, please refer to the tables below.

Sapphire substrate, silicon substrate, and silicon carbide substrate are the three commonly used substrate materials for making LED chips. The luminous efficiency of sapphire substrate white LED has exceeded 150lm/W, and the laboratory level has exceeded 200lm/W. At the same time, the silicon substrate white light LED with independent technical property rights has reached 150lm/W. In terms of light efficiency, LED lighting has reached the standard of replacing traditional light sources. Therefore, the market penetration rate of LED lighting will rise rapidly.

LED wafer on silicon


1. Specifications of LED Wafer on Silicon

1.1 LED Epiwafer on Silicon for Blue Light(mainly used in MicroLED display products)

Item Parameters
Micro LED Wafer Size 2’’, 4”, 6” and 8”
Orientation C-axis(0001)+/-1°
P-(AlIn)GaN 120 – 170 nm, [Mg] > 1E19/cm3
InGaN/GaN Multiple Quantum Wells 100 – 200 nm
nGaN  1.40 – 1.60 um, [Si] ~ 5.0E18/cm3
Buffer 1.50 – 1.70 um
Average Dominant Wavelength 450 ~ 470 nm
Wafer bow < ±50 um
FWHM < 20 nm
Substrate Si(111)
Substrate Thickness 100 mm 800 um
150 mm 1 mm
200 mm 1.15 mm


1.2 LED Wafer on Silicon for Green Light

Item Parameters
Size 2’’, 4”, 6” and 8”
Orientation C-axis(0001)+/-1°
P-(AlIn)GaN 100 – 170 nm, [Mg] > 1E19/cm3
InGaN/GaN Multiple Quantum Wells 200 – 300 nm
nGaN  1.40 – 1.60 um, [Si] ~ 5.0E18/cm3
Buffer 1.50 – 1.70 um
Average Dominant Wavelength 500 ~ 520 nm
Wafer bow < ±50 um
FWHM < 40 nm
Substrate Si(111)
Substrate Thickness 100 mm 800 um
150 mm 1 mm
200 mm 1.15 mm

2. LED Wafer Fabrication: we can offer fabrication service, you can separately order lift off and flip-chip bonding service, or full process of chip making.

2.1 Preparation of III-N LED Wafer:

Make sure Top (n-side up) surface quality before epitaxial lift-off and bonding.

2.2 Epitaxial Lift Off and Flip-Chip Bonding Specification:

a. Surface and material quality after bonding is same or better than starting wafer:Viable for n-contact formation for microLED applications;

b. Bonding metal / material to Si carrier wafer is highly conductive (lower resistivity than Si carrier wafer see below);

c. Si carrier wafer is highly conductive (low resistivity ~0.001-0.005 ohm-cm or less) to enable backside p-contact formation;

d. Si carrier wafer is clean (same LED wafer starting surface): No grease, grit or particles;

e. Si carrier wafer should be thick enough to handle with tweezers without shattering:

  • 300 µm or 500um (+/- 10%) Si  available;
  • To satisfy conductivity and contact formation requirements thinner wafer can be specified but we would need to review this.

2.3 Clean purchased samples as received:

a. Pattern samples with dual-tone photoresist (multiple steps): Develop in TMAH based developer;

b. Perform RIE where necessary;

c. Surface treatment of samples in dilute KOH solution under heated conditions;

d. Metalize (e-beam evaporation) top of mesa with n-contact metal;

e. Metalize (e-beam evaporation) backside of conductive Si wafer or bottom of mesa with p-contact metal: Anneal p-contact with RTA.

3. Why Choose Silicon-based LED Wafer for MicroLED Applications?

The reasons for choosing silicon-base LED wafer solutions for microLED applications are illustrated below:

Firstly, silicon can have a diameter of up to 300 mm, and the cost is low.

Secondly, since the particles are embedded on the surface during the growth process and damage the quality of the material, the fewer the particles, the better the quality of the epitaxial wafer. Silicon can provide a good substrate for high-quality and low-particle-level LED epi wafer.

More importantly, GaN-on-silicon has the advantage of being compatible with mature silicon-based manufacturing. This manufacturing technology for LED wafer production is very mature and can be used for monolithic integration of thin film processes and arrays.

Finally, appropriate strain engineering techniques can be used in GaN-on-silicon LED epitaxial wafers to achieve good uniformity and minimal warpage.

A large number of tests of PAM-XIAMEN GaN LED wafer on silicon show that they have a strong potential for the preparation of microLEDs. PAM-XIAMEN LED wafer material has a wafer warpage below 30μm, an internal quantum efficiency of over 80% and good wavelength uniformity, which can well support the productivity ramp-up of microLED display manufacturing.

4. FAQ of GaN LED Wafer

Q1:Do we have to activate the p-type GaN on silicon below, i.e., perform a thermal cycle to have hydrogen out-diffuse, or was this step already done at your facility?


Layer No. Material Thickness
8 P++ GaN
7 P-GaN
6 P-AlGaN
4 N-GaN
3 Undoped GaN 500nm
2 AlGaN buffer
1 AlN
Si (111) substrate


A:Yes, you should activate the Si-based p-type GaN under N2 at a certain degree for several minutes (190609). For more details, please contact victorchan@powerwaywafer.com.

Q2: What is highest p-type dopant concentration for the top layer of blue LED epitaxial Wafers (GaN or AlGaN) ?

 A: Mg doping concentration for the top layer of the blue GaN LED wafer is (1-5)E20, and Mg activation efficiency is 1%, so after activation, Mg doping concentration should be (1-5)E18.

Q3: Can you share the CTLM data with us of your ITO on your p-GaN/Si LED wafer?

A: We adopt four probe test method to test the GaN on Silicon LED wafer with ITO layer, and the corresponding data: at present, there are only the maximum, minimum and typical values:

Test Item Condition Parameter Min.value Typical value Max value
test resistivity after Annealing p-GaN contact 1.00E-04 4.20E-04 1.00E-03


Q4: What is the method you use to deposit ITO on GaN/Si LED structure?

A: We deposit ITO on Si based LED structure by sputter.

For more information, please contact us email at victorchan@powerwaywafer.com and powerwaymaterial@gmail.com.

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