Nitrides Seminar - Yi Chao Chow, Graduate Student Researcher, Materials

11/18/2021 12:00PM ESB 1001 & on Zoom

Nitrides Seminar

Thursday,November 18,2021, 12:00PM

Attend in person at ESB 1001!


Zoom option also available

Meeting ID: 833 7178 9044             Passcode: 321901


Yi Chao Chow
Graduate Student Researcher, Speck Group

University of California, Santa Barbara


Controlling the internal electric field with doped barriers
in c-plane InGaN/GaN LEDs



Large spontaneous and piezoelectric polarization exists in wurtzite III-nitride materials. The polarization charges at the heterointerfaces induce large electric fields along the [0001] c-axis which coincides with the typical growth direction of III-nitride optoelectronic devices. For visible InGaN/GaN LEDs, the resulting large internal electric field in the InGaN quantum well causes a spatial separation of electron and hole wavefunctions. The reduction in wavefunction overlap leads to lower recombination rates which are detrimental to the LED performance.


Doped barriers were used in c-plane InGaN/GaN single quantum well LEDs with the aim of reducing the internal electric field in the quantum well. Through biased photocurrent spectroscopy, we indeed observed a reduction in the net internal electric field. The ability to control and reduce the internal electric field in the QW allows unconventional active region design in c-plane LEDs. Thick quantum well can be used to increase the active region volume and reduce the carrier density, thereby delaying the onset of the efficiency droop. With doped barriers, we demonstrated c-plane InGaN/GaN LEDs with low efficiency droop using a 9-nm-thick single quantum well.



HOST: Dr. Tal Margalith