Rapid degradation phenomenon in heterojunction GaAlAs–GaAs lasers

Abstract

The rapid degradation phenomenon in Ga1−xAlxAs–GaAs DH lasers has been associated with the growth of a dislocation network during the device operation. The nature of these defects has been analyzed by transmission electron microscopy in an effort to understand their origin and growth mechanism. The propagation of the dislocation network is found to take place by successive climb of a dislocation crossing the n-Ga1−xAlxAs, p-GaAs, and p-Ga1−xAlxAs layers in the stripe area. The climb process leads to the formation of a three-dimensional dislocation dipole network which extends through the three epitaxial layers and remains confined to the stripe area. A tentative model which discusses the network growth process is presented. The source of the very large vacancy concentration involved in the climb process has been attributed to the interfaces between the binary and ternary layers. The fast climb rate has been related to large drift forces acting on the vacancies during the device operation. The dominant drift forces are thought to be electrical and elastic in nature.

A brief history of defect formation, segregation, faceting, and twinning in melt-grown semiconductors

“…Not only can they substitute on both sub-lattices of a binary compound, they can also form complexes with charged vacancies to produce compensating deep levels [11]. The interaction of native point defects with dislocations can have a dramatic effect on the lifetime of lasers in some III-V compounds [20].…”

Epitaxial growth of highly mismatched III-V materials on (001) silicon for electronics and optoelectronics

“…In general, most of previous QW lasers on Si suffered from poor reliability and short lifetimes, impeding their practical application. The rapid degradation was attributed to the formation of dark line defects [89][90][91][92][93][94][95]. Fig.…”

Combined transmission electron microscopy and cathodoluminescence studies of degradation in electron-beam-pumped Zn1−xCdxSe/ZnSe blue-green lasers

“…27 We therefore conclude that degradation occurred through recombination-enhanced dislocation climb, consistent with most degradation studies of III-V devices. 36,38 The mechanism of dislocation climb is not yet completely understood, but it is known to be nonconservative, and requires that point defects of both constituents ͑e.g., Zn and Se vacancies͒ be added or removed simultaneously from the dislocation core in order to preserve the stability of the sphalerite structure. The most recent model, proposed by Vardya and Mahajan, 39 states that only one defect ͑Se or Zn vacancy, V Se , V Zn , or Se or Zn interstitial, Se i , Zn i ͒ has to reach the dislocation core in order to initiate the climb, and that the defect of the other constituent is generated in situ.…”