Low injection losses in InGaN/GaN LEDs: The correlation of photoluminescence, electroluminescence, and photocurrent measurements

Defects and Reliability of GaN‐Based LEDs: Review and Perspectives

“…The presence of defects within or close to the active region can favor SRH recombination and drastically lower the radiative efficiency of the devices. [ 67 ] To better evaluate this aspect, we implemented TCAD simulation deck aimed at studying the impact that traps location, rather than trap type, has on the optical performance of a typical blue InGaN SQW LED. The simulated structure, shown in Figure a and implemented by means of Crosslight Apsys software suite, consists of a 2.5 μm n‐GaN:Si layer ( N D = 3 × 10 18 cm −3 ), a 20 nm quantum barrier (QB) (labeled n‐side QB), a 2 nm In 0.2 Ga 0.8 N QW, a 10 nm QB (labeled p‐side QB), a 20 nm Al 0.2 Ga 0.8 N p‐doped EBL ( N A = 5 × 10 19 cm −3 ) and a 200 nm p‐doped GaN:Mg layer ( N A = 5 × 10 19 cm −3 ).…”

“…The presence of defects within or close to the active region can favor SRH recombination and drastically lower the radiative efficiency of the devices. [67] To better evaluate this aspect, we implemented TCAD simulation deck aimed at studying the The band diagram of the ideal structure with no traps, simulated at an injection level of J ¼ 40 A cm À2 , is shown in Figure 10b. We highlighted with different colors the regions where traps have been selectively introduced.…”

Spectral-temporal study on the output power of green InGaN LEDs

“…While this shift is large, even larger shifts have been observed for blue LEDs with wide QW, e.g. a blue-shift of approximately 15 for a 465 nm LED when the bias was decrease from forward bias to V bias = 1.4 V. 26) However, while this paper reported a strong change in carrier life time with excitation power and wavelength, it did not report on the dependency of carrier life time on bias voltage. In our experiment, with increasing current densities, the wavelength at τ 1 is blue-shifted while the wavelength at τ 2 experiences a smaller blue-shift for zero and small reverse bias, and no blue-shift for −3 V reverse bias.…”

“…22) We suggested to use this effect to modify and possibly increase LED efficiency by a pulsed mode operation, where carrier injection and carrier recombination occur at different bias: carriers are injected into the QWs during a forward bias, and recombine during a reverse bias when the overlap of electron and hole wave functions are maximized. 23) While the general findings of the impact on bias were confirmed, [24][25][26] the approach did not yet result in a successful demonstration of droop reduction in LEDs. One reason is that state-of-the-art LEDs are optimized for efficiency at forward bias, such minimizing the effect of reverse bias on carrier recombination.…”

Mid-infrared photoluminescence revealing internal quantum efficiency enhancement of type-I and type-II InAs core/shell nanowires

“…The PL efficiency η is defined as η = I/P , the ratio of the PL integral intensity (I) to pumping power (P ). 42 For comparison, the PL efficiencies at a pumping power of 10 mW are normalized to unity. Clearly, the PL efficiencies decrease monotonously as pumping power increases, which reveals the Auger recombination dominating the PL process.…”