In this study, AlN epilayers were grwron on the 2inch patterned shapphire substrate (PSS) using mixed source HVPE.
The gaseous metal chlorides, which is reaction of metallic aluminum with HCl gas was used for III group source and V group source was NH3 gas. N2 gas was flowed for a stable growth atmosphere. The source boat was graphite in order to use the RF induction heating method. The temperature of the source zone and the growth zone of HVPE were set at 750℃ and 1145℃ respectively.
In order to observe mechanism of the growth AlN epilayer on PSS, the experiment is divide into two phases. step I, in accordance with the V/III ratio of the initial growth mode AlN and step II, AlN growth mode of the growth time.
The surface and cross-section images of AlN epilayer on PSS were observe by SEM. To analysis the components of AlN epilayers, we used EDS, which is attacched to SEM.
The HCl gas flow of step I is 30, 60, 100 sccm and the growthtime is 5 hour, respectively.
The step II with condition for V/III = 30 , HCl gas flow 100 sccm and the up to 64hours growth time.
finally, one pattern for growing to hexagonal shape. also the c-plane growth rate was faster than hexagonal (100), (011), (1-10), (101), (-101), (1-11).
The structure characteristics of AlN epilayers were studied by XRD using the FWHM and 2theta peak. The FWHM at 64hr was smaller than 3hr. The lattice constants can be calculated with Bragg's formula and XRD reslults.
we know the growth mechanism of AlN epilayer on PSS by mixed source HVPE.
As a result, we grwon AlN epilayer on PSS. but we have to most stable condition of flat AlN epilayer, such as improve HCl ratio, growth time and sample rotation on growth zone.