lauren cantley presentation

Lauren Cantley

Part of the family of group II-IV nitride semiconductors

Closely related to group III nitrides◦ Band gap◦ Crystal lattice structure

To date there has been no reported growth of ZnSnN2

ZnSnN2 predicted to be analogous to InN

Because of their similar properties, group II-IV nitrides are predicted to have similar applications as group III nitrides

Also expected to be superior to group III nitrides in certain instances◦ Predicted to have smaller range of lattice

constants for same band gap range◦ Could resolve issues associated with clustering

To synthesize ZnSnN2 – completing the first ever reported growth!

To determine the optimal conditions under which the growth of ZnSnN2 can occur

High Vacuum Plasma System◦ RF plasma source◦ Vacuum pumps and

chamber◦ Experimental

package◦ Crucible and heater◦ Various gauges to

monitor growth conditions

o Experimental packageo Crucible and heater

Zinc is volatile However, evaporation of zinc can be

suppressed within a Zn-Sn liquid alloy rich in tin

Also can suppress evaporation by working at higher pressures

Metals must melt and form a liquid alloy at a temperature lower than the growth temperature

No conflicts of interest between suppressing the vapor pressure of zinc and melting the alloy together

Zinc oxidizes readily under normal atmospheric conditions

Oxide layer melts at temperatures higher than the range of the heater

If Oxide layer present, Zinc won’t coalesce Remove oxide layer by flowing hydrogen

plasma into the system

Pressure: 150 mTorr Temperature: 400 C or 500 C Composition of Zn-Sn alloy melt:

10 wt% Zn90 wt% Sn

Growth period: 4.5 hours Plasma:

◦ 60 watts forward power◦ 10 sccm of nitrogen◦ 5 sccm of hydrogen

Growth temperature: 400 C Nitrogen plasma off during

coolingMagnification: 20x

XEDS

X-ray energy dispersive spectroscopy

X-Ray Mapping

N

Zn

Sn

300μ

m

300μm

Growth temperature: 400 C

Nitrogen plasma on during cooling

Magnification: 50x

Magnification: 10x

Growth temperature: 500 C Nitrogen plasma on during cooling until sample

reached 400 C

No film was found on the surface of the sample Sample was found to have a 9.1 wt% loss in mass

after growth period. Initial composition of the sample was 9.1 wt% zinc

Leads us to believe all the zinc evaporated at the higher temperature

Material grown on the surface of sample 1 most likely to be ZnSnN2

Unable to confirm the growth of ZnSnN2

Unable to fully explore phase space in which ZnSnN2 is presumed to be stable

However, these initial growths are a good starting point for further research