Nitride facet passivation raises reliability, COMD, and enables high-temperature operation of InGaAsP, InGaAs, and InAlGaAs lasers

Abstract

The laser diode technology, underpinning applications such as data storage, industrial lasers and optical telecommunications, still suffers from reliability and longevity limitations, especially in high power applications. A main problem for these lasers arises from facet oxidation, leading to increased absorption, power degradation and COMD device failure. Typically, high power devices initially show a low linear degradation and after some 100 hours, the degradation accelerates in a nonlinear fashion, indicating a degradation runaway condition. This article reports performance and reliability improvements that are based on a process which atomically seals surfaces and eliminates oxidation by forming stable nitrides on laser facets. The dangling bond terminating technology suppresses accelerated degradation associated with optical density and heat at laser facets. The dangling bond termination is demonstrated by improved COMD, decreased degradation at CW operation and a constant linear degradation rate at different QW temperature conditions (nonlinear degradation indicates advancement in the oxidation/optical absorption/facet heating/oxidation spiral). The technology is applicable to a range of material systems and has previously been demonstrated on InAlGaAs and InGaAs (increased COMD to >270 and 470mW/µm respectively). The devices with the typically lowest COMD levels (AlInGaAs) show a remarkably low linear degradation rate of <0.5%/kh during at CW life test operation at 90˚C and a power level corresponding to 80W bar power. In addition to long term AlInGaAs laser life test results, this paper presents results on nitride facet passivation applied to 805nm InGaAsP devices, showing improved COMD to 400mW/µm and the initial CW life data confirms the general behavior of the previously life-tested InGaAs and InAlGaAs based devices.

Влияние ионной очистки поверхности излучающего скола 9хх нм лазерных диодов на основе InGaAs/AlGaAs/GaAs на их предельную мощность излучения

“…Второй подход заключается в том, что во время скалывания не принимаются меры по предотвращению окисления, но перед осаждением защитного покрытия проводится ионная очистка поверхности низкоэнергетичными ионами водорода [10][11][12][13], азота [13,14] либо аргона [15,16] с целью удаления образовавшихся во время выдержки в атмосфере окислов. Второй подход более прост в реализации, так как не требует манипуляций с хрупкой полупроводниковой пластиной в вакууме или в инертной среде, однако из-за возможности образования радиационных дефектов ряд авторов отмечают, что обработка низкоэнергетичными ионами может привести к снижению предельной мощности и сроку службы лазерных диодов [4,17].…”

Influence of ion cleaning of front facet of 9xx nm InGaAs/AlGaAs/GaAs diode lasers on their maximal output power

“…The second approach is that no measures are taken to prevent oxidation during cleavage, but before the deposition of the protective coating, ion cleaning of the surface is conducted with low-energy hydrogen ions [10][11][12][13], nitrogen [13,14] or argon [15,16] to remove oxides formed during exposure in the atmosphere. The second approach is easier to implement, since it does not require manipulations with a fragile semiconductor wafer in a vacuum or in an inert medium, however, due to the possibility of radiation defects, a number of authors note that treatment with low-energy ions can reduce the maximum output power and service laser diode lifetime [4,17].…”