GaN Blue Laser Diodes by kanyai tt .pptx

Gan blue laser presentation

1. GaN Blue Laser Diodes: Technology, Applications, and Future Trends Kanyai TT

2. Introduction GaN -based blue laser diodes (LDs) are pivotal in modern optoelectronics, enabling high-power, short-wavelength emission for diverse applications. Their development stems from breakthroughs in GaN material science and epitaxial growth. Wavelength Range: 405–450 nm (key for high-density optical storage). Power Efficiency:2–5x higher than traditional DPSS lasers. Thermal Stability: Operates up to 80°C+ due to wide bandgap (3.4 eV for GaN ). Compactness: Enables portable devices (e.g., handheld projectors).

3. Why GaN blue laser diodes are revolutionary

4. 📜 Historical Development

5. 📜 Historical Development continued… 1990:Nakamura ’ s team at Nichia achieved p-type GaN doping (Mg + thermal annealing). 1996: First commercial InGaN MQW LD (pulsed, then CW by 1999). 2010s:Emergence of GaN -on- GaN homoepitaxy (reducing dislocation density to <10 ⁶ cm ⁻² .

6. How GaN Blue Lasers Work Laser diodes operate via stimulated emission in a forward-biased p-n junction. Photons are amplified in an optical cavity formed by cleaved facets (mirrors). Stimulated emission in InGaN quantum wells creates coherent 450 nm light

7. Anatomy of a GaN Laser Diode Substrate: Sapphire/ SiC / GaN (lattice-matched GaN preferred). Buffer Layer: AlN / GaN to reduce threading dislocations. n- GaN Cladding: Si-doped for electron injection. Active Region: InGaN / GaN MQWs (3 – 5 wells, ~3 nm thick). p- GaN Cladding: Mg-doped + annealed.

8. Growing Perfect GaN Crystals 1. **Precursor Injection** ( TMGa + NH ₃ → GaN + byproducts). 2. **Nucleation Layer** (Low-temp AlN / GaN buffers). 3. **High-Temp Growth** ( InGaN QWs at 800 – 1000 ° C).

9. *Engineering Light with Quantum Wells* **Visual:** - **Animated Band Diagram:** - **Step 1:** Show flat bands (no bias). - **Step 2:** Add forward bias → electrons/holes flood QWs. - **Step 3:** Photon emission (blue flash). **Critical Parameters:** - **Well Thickness:** 2 – 4 nm (optimal for 450 nm light). - **Barrier Material:** Al ₀ . ₁ Ga ₀ . ₉ N (prevents carrier leakage). **Callout:** *"Thinner wells = higher efficiency but harder to grow!"*

10. Engineering Light with Quantum Wells - **Step 1:** Show flat bands (no bias). - **Step 2:** Add forward bias → electrons/holes flood QWs. - **Step 3:** Photon emission (blue flash). **Critical Parameters:** - **Well Thickness:** 2 – 4 nm (optimal for 450 nm light). - **Barrier Material:** Al ₀ . ₁ Ga ₀ . ₉ N (prevents carrier leakage). **Callout:** *"Thinner wells = higher efficiency but harder to grow!"*

11. Breakthroughs That Made GaN Lasers Possible 1. **Two-Flow MOCVD:** - *Image:* Nakamura ’ s reactor patent diagram. - *Impact:* Dropped defect density 1000x. 2. **p-Type Activation:** - *Graph:* Hole concentration vs. annealing temp (peak at 700 ° C). 3. **ELOG Substrates:** - *SEM Image:* Dislocations "bending" away from active region. **Quote:** *"Without these innovations, GaN lasers would still be lab curiosities."*

12. GaN Lasers in Action 1. **Entertainment:** - *Sony ’ s 4K projectors* (laser phosphor tech). - Icon: Movie reel. 2. **Industry:** - *Precision welding of copper* (800W lasers). - Icon: Robot arm. 3. **Medicine:** - *Cancer detection* (405 nm fluorescence imaging). - Icon: DNA helix.

13. Overcoming the Roadblocks | **Challenge** | **Solution** | **Status** | |-------------------------|-----------------------------------|--------------------------| | Defects (10 ⁸ cm ⁻² ) | ELOG substrates (10 ⁶ cm ⁻² ) | ✅ Commercialized | | Green Gap (500 – 550 nm) | Semipolar GaN | 🧪 Lab-stage (2024) | | Cost ($50/diode) | 6-inch GaN -on-Si wafers | ⏳ Pilot production |

14. The Next Decade of GaN Lasers **2025:** 50W single emitters (LiDAR). - **2030:** $10/diode (consumer markets). - **2035:** Direct green lasers (displays). **Quote:** *" GaN could dominate the $10B laser market by 2030."*

15. Conclusion: The Blue Laser Revolution Has Just Begun 1. **Summary:** 3 key takeaways (efficiency, applications, future). 2. **Question:** *"Will GaN lasers make traditional LEDs obsolete?"* 3. **Contact:** Your email/QR code for further discussion.