Heidi Marie Dieringer

InGaN/GaN lasers grown on SiC

Single crystal thin films with compositions from the AlN-InN- GaN system were grown via metal-organic chemical vapor deposition (MOCVD) on single crystal 6H-SiC substrates. Blue light emitting (LED) and laser diode (LD) structures were fabricated. A conducting buffer layer was developed which uses an AlGaN buffer layer which provides a conduction path between SiC and the active device region. This conducting buffer layer was utilized in both the LEDs and the LDs. The external quantum efficiency of the LEDs was 3% at 20 mA (3.6V) with a peak emission wavelength of 430 nm. Violet and blue LDs were fabricated which consisted of an 8-well InGaN/GaN multiple quantum well (MQW) active region in a separate confinement heterostructure (SCH) design. The devices lased at room temperature under pulsed and continuous wave operation with an emission wavelength of 404-435 nm. The lowest pulsed operation threshold current density obtained for lasing under was 10.4 kA/cm2.

InGaN/GaN MQW SCH lasers grown on SiC

Laser diode structures were fabricated by metal-organic chemical vapor deposition (MOCVD) from the AlN-InN-GaN system on single crystal 6H-SiC substrates. An AlGaN conducting buffer layer was developed for these devices, which provides a vertical conduction path between SiC substrate and the active device region. Violet and blue multiple quantum well (MQW) separate confinement heterojunction (SCH) LDs were fabricated having InGaN wells and GaN barriers. The lowest pulsed operation room temperature threshold current density obtained for lasing was 7.1 kA/cm2 in a 4-well structure. Lasing has also been obtained in these same devices at duty cycles up to 75%.