When building a diversified investment portfolio, investors may turn to various dividend-paying stock exchange traded funds to generate some extra income.

In an environment of near-zero interest rates and quantitative easing, dividend stocks have attracted investors seeking a better source of income, Ben Johnson, director of global ETF research at Morningstar, said.

When searching for a dividend stock, investors may turn down two different avenues: dividend growers or high-yielding stocks.

“So the growers are those strategies that look to build a portfolio of individual stocks that have grown their dividends with time,” Johnson said. “They show consistent, very reliable, and ideally growing dividend payouts. Now the yielders are a whole nother cohort. The yielders and the underlying benchmarks of the ETFs that look to isolate the yielders screen first and foremost on the basis of yield…. They’re just looking for that headline yield they are not necessarily screening for sustainability and growth of that income stream.”

For instance, investors seeking stable dividend growers may turn to something like the Schwab US Dividend Equity ETF (NYSEArca: SCHD), which includes 100 stocks based on strong fundamentals, dividend yields and consistent dividend payouts for at least 10 consecutive years. SCHD has a 2.94% 12-month yield, comes with a cheap 0.07% expense ratio and can be traded commission-free on the Schwab platform.

“If you look at the percentage of the portfolio’s assets that are in either wide- or narrow-moat firms it’s nearly 100%,” Johnson said. “So these are very high-quality firms, with sustainable competitive advantages that allow them to preserve and ideally grow over time, those cash flows that they are sharing with investors in the form of dividends.”

Investors who are just looking for high yields may take a look at something like the Vanguard High Dividend Yield ETF (NYSEArca: VYM), which has a 3.11% 12-month yield and a 0.10% expense ratio. VYM tries to reflect the performance of the FTSE High Dividend Yield Index, which specifically targets quality stocks with high dividend yields.

“So amongst all of the dividend strategies that we would categorize as yielders, it’s got the most moaty portfolio,” Johnson added, referring to VYM’s portfolio of stocks with high economic moats or competitive advantages.

For more information on dividend stocks, visit our dividend ETFs category.

Max Chen contributed to this article.