**2.1 Growth of nitride-based reflectors and micro-cavity**

The detail growth process and experiment parameters of the micro-cavity and nitride-based DBR on sapphire substrates by metal organic chemical vapor deposition (MOCVD) are described as follows:

First, the substrate was thermally cleaned in the hydrogen ambient for 5 min at 1100 °C. And then, a 30 nm-thick GaN nucleation layer was grown at 500°C. The growth temperature was raised up to 1100 °C for the growth of a 2 µm-thick GaN buffer layer. The subsequent epitaxial structure consisted of a 29-pair of quarter-wave AlN/GaN DBR grown at 1100 °C, a 7-lamda cavity ( = 410 nm) which includes a 860 nm-thick Si-doped n-GaN layer, 10 pairs In0.2Ga0.8N/GaN (2.5 nm/12.5 nm) MQWs, a 24 nm-thick AlGaN layer as the electron blocking layer, a 110 nm-thick Mg-doped p-GaN layer, and a 2 nm-thick p+ InGaN layer as the contact layer. The AlN/GaN super-lattices (SL) inserted in the stacks of 29-pair AlN/GaN layers are fabricated because they can release the strain during the growth of AlN/GaN DBR and further improve interface and raise reflectivity of the DBR. Besides, the AlN/GaN DBR can play the role of the low refractive index layer to confine the optical field in the active region in the whole structure. And then, the AlGaN electron blocking layer was served to reduce the electron overflow to the p-GaN layer. The reflectivity spectrum of the AlN/GaN DBR is shown in Fig. 1. It shows the highest reflectivity of the DBR is about 99% at 416 nm. The stop-band of the DBR is as wide as about 25 nm. Fig. 2. is (a) the OM and (b) cross-sectional TEM images of the as-grown micro-cavity sample.

Fig. 1. The reflectivity spectrum of the AlN/GaN

Here, the fabrication processes are composed of two parts. One is the epitaxial growth on sapphire substrates by metal organic chemical vapour deposition (MOCVD), including a 29 pair distributed Bragg reflectors (DBR), a p-GaN layer, multi-quantum wells, a n-GaN, and a un-doped GaN layer, etc. Another one is to fabricate the PhC nanostructure on the epitaxial wafers by the E-beam lithography system and inductive coupled plasma reactive ion etching (ICP-RIE) system. Finally, the GaN-based photonic crystal surface emitting laser

The detail growth process and experiment parameters of the micro-cavity and nitride-based DBR on sapphire substrates by metal organic chemical vapor deposition (MOCVD) are

First, the substrate was thermally cleaned in the hydrogen ambient for 5 min at 1100 °C. And then, a 30 nm-thick GaN nucleation layer was grown at 500°C. The growth temperature was raised up to 1100 °C for the growth of a 2 µm-thick GaN buffer layer. The subsequent epitaxial structure consisted of a 29-pair of quarter-wave AlN/GaN DBR grown at 1100 °C, a 7-lamda cavity ( = 410 nm) which includes a 860 nm-thick Si-doped n-GaN layer, 10 pairs In0.2Ga0.8N/GaN (2.5 nm/12.5 nm) MQWs, a 24 nm-thick AlGaN layer as the electron blocking layer, a 110 nm-thick Mg-doped p-GaN layer, and a 2 nm-thick p+ InGaN layer as the contact layer. The AlN/GaN super-lattices (SL) inserted in the stacks of 29-pair AlN/GaN layers are fabricated because they can release the strain during the growth of AlN/GaN DBR and further improve interface and raise reflectivity of the DBR. Besides, the AlN/GaN DBR can play the role of the low refractive index layer to confine the optical field in the active region in the whole structure. And then, the AlGaN electron blocking layer was served to reduce the electron overflow to the p-GaN layer. The reflectivity spectrum of the AlN/GaN DBR is shown in Fig. 1. It shows the highest reflectivity of the DBR is about 99% at 416 nm. The stop-band of the DBR is as wide as about 25 nm. Fig. 2. is (a) the OM and (b)

**2. Fabrication processes** 

described as follows:

(PCSEL) devices with AlN/GaN DBR are performed.

**2.1 Growth of nitride-based reflectors and micro-cavity** 

cross-sectional TEM images of the as-grown micro-cavity sample.

Fig. 1. The reflectivity spectrum of the AlN/GaN

**99% at 416nm**
