Zinc diffusion in InP using diethylzinc and phosphine

Abstract

A low pressure open tube system with diethylzinc (DEZn) and phosphine (PH3) as precursors was used to study the Zn-diffusion in InP. This system offers a flexible and precise control of the diffusion parameters. We investigated the effect of the DEZn and PH3 partial pressures and of the diffusion temperature and time on the hole and Zn concentration profiles. Annealing the samples leads to an increased hole concentration due to out-diffusion of interstitial Zn donors. The Zn and hole concentration profiles were obtained by secondary-ion mass spectroscopy and C–V etch profiling showing maximum hole concentrations between 1017 cm−3 and 4×1018 cm−3 for diffusion depths from 0.3 to 2 μm.

InP nanowire p-type doping via Zinc indiffusion

“…Further increase in the diffusion temperature to 500 °C gave additional ~50 % increase in carrier concentration and conductivity compared to the 425 °C diffused sample. This corresponds well to the literature, where optimal temperatures have been reported around 500 °C 10,29,30 . The optimal temperature range results from zinc phosphide growth at lower temperatures and evaporation of Zn species at higher temperatures 29,30 .…”

“…Post-annealing is an essential part of the diffusion doping process, since a considerable part of the diffused Zn take interstitial positions (Zn i ), where they can act as donors and compensate the p-type doping 10,12,16,28,30 . Additionally, hydrogen can effectively passivate Zn acceptors 31 .…”

“…Additionally, hydrogen can effectively passivate Zn acceptors 31 . The post-annealing process activates the interstitial Zn i to substitutional positions (Zn s ), and outdiffuses mainly the Zn i and hydrogen 16,28,30 . In addition, a slow loss of Zn s is indicated by a reduced carrier concentration after prolonged (8 h) annealing in earlier work 16 .…”

Multiwafer zinc diffusion in an OMVPE reactor

“…In agreement with earlier studies using sealed ampoule diffusion [6] and OMVPE diffusion [3], the maximum hole concentration after diffusion but before annealing is between 20-50% of the maximum Zn concentration; this increases to 30-75% after a post-diffusion RTA using the annealing conditions detailed above. Two mechanisms have been proposed to account for the lower hole concentration compared to the total Zn concentration: passivation of the Zn by atomic hydrogen [7,8], or compensation of the substitutional Zn by an interstitial donor [6,9]. An increase in hole concentration after annealing is consistent with either mechanism.…”

Stability of Zn doping profile in modulation-doped multiple quantum well structure

“…21 The often observed high diffusivity of Zn atoms would seem to restrict the possibility of getting abrupt doping profiles. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] However, doping superlattices ͑so-called nipi structure͒ with Zn as p-type dopant have been successfully fabricated. [22][23][24][25] Furthermore, a small Zn diffusion coefficient of 6.5ϫ10 Ϫ14 cm 2 /s has been reported in the case of unin-tentional diffusion.…”