4.4 Two-Step Growth Method for MOCVD Grown Nitride Materials
51
(3) Stranski-Krastanovs mode: It begins with layered growth in one or two atomic
layer thicknesses, and then is converted into island-like growth. That is, firstly
the layered growth mode and then converted to the island growth mode.
Of the above three growth modes, the latter two modes are three-dimensional
growth. At the atomic scale, producing a smooth and uniform film means layered
growth or two-dimensional growth, instead of three-dimensional growth.
The MOCVD growth process of GaN materials also follows surface dynamics
of thin film growth. Therefore, many experimental phenomena observed during the
growth of GaN can be explained by this theory. The following is a brief introduction
to the common MOCVD two-step growth procedure of GaN on sapphire.
4.4.2 Two-Step Growth Program for GaN/Sapphire
by MOCVD
Figure 4.6 shows the in situ monitoring reflectance curve of MOCVD growth of
GaN materials. Generally speaking, the two-step growth of intrinsic GaN materials
requires the following steps:
(1) First, high temperature treatment at 1100 °C is carried out for 15 min under
H 2 atmosphere. This procedure will eliminate surface contamination of the
substrate.
Fig. 4.6 In-situ monitoring curve of GaN growth
51
(3) Stranski-Krastanovs mode: It begins with layered growth in one or two atomic
layer thicknesses, and then is converted into island-like growth. That is, firstly
the layered growth mode and then converted to the island growth mode.
Of the above three growth modes, the latter two modes are three-dimensional
growth. At the atomic scale, producing a smooth and uniform film means layered
growth or two-dimensional growth, instead of three-dimensional growth.
The MOCVD growth process of GaN materials also follows surface dynamics
of thin film growth. Therefore, many experimental phenomena observed during the
growth of GaN can be explained by this theory. The following is a brief introduction
to the common MOCVD two-step growth procedure of GaN on sapphire.
4.4.2 Two-Step Growth Program for GaN/Sapphire
by MOCVD
Figure 4.6 shows the in situ monitoring reflectance curve of MOCVD growth of
GaN materials. Generally speaking, the two-step growth of intrinsic GaN materials
requires the following steps:
(1) First, high temperature treatment at 1100 °C is carried out for 15 min under
H 2 atmosphere. This procedure will eliminate surface contamination of the
substrate.
Fig. 4.6 In-situ monitoring curve of GaN growth